Thank you for the PM. I will reply here but feel free to PM me if I can help further.
There is a very significant difference in price, but I gather this may not be an issue. Never the less money is money. I guess there are some obvious financial considerations which may include the market for Diamonds being soft at the moment because of the problems the company has encountered. I also guess the jury may be out on whether Diamond survive and what impact this will have on resale values if they do not. On the positive side of the curve I suspect they have enough critical mass in terms of aircraft sold for someone to pick up the pieces if the worst happens. On the other side of the scale with the dollar in the ascent at the moment it may not be the best time to purchase an aircraft priced in dollars.
Leaving these issues aside in my opinion there is no doubt a new PPL would be able to fly the Diamond with relatively little instruction. On the other hand the Cirrius is, as single GA aircraft go, a relatively high performance machine. I cruise at around 160 knots for a reasonable fuel burn (it will go quicker). It is slippery, so a new PPL must get use to the usual issues focused around slowing down a fast aircraft and accustom to the changes in the scenery being going past more quickly.
Those that regularly convert people onto these aircraft will tell you that it can take 20 or more hours for a low time pilot to get comfortable with the Cirrus, whereas maybe a quarter of that for the Diamond.
Interior
The interior fit of the Diamond gives the impression of being made to a price and a weight. The furnishings are pleasant enough, but little appears “over engineered” - the bucket seats for example are fixed and give the impression of a glass fibre frame covered in a layer of good quality leather. That said I think the quality of the build for a plastic aircraft is as good as the Cirrus and generally both are of a high standard. Clearly you expect a lot more for your money with the Cirrus so it is not surprising that the interior of the Cirrus is very well appointed with perhaps the best seats I have found in any single and a well formed and put together interior. I always say perhaps disingenuously it was designed for big Americans. If you are seriously touring you would undoubtedly find the Cirrus more comfortable than the Diamond after three or fours hours in the Aircraft, the more especially if you are confined to the rear seats.
Avionics.
The Cirrus comes with the Avidyne system, the Diamond with the G1000. Both work well and in terms of day to day operation I don’t think there is much between the two. The Avidyne I think is a little easier to grasp and a bit more intuitive. I don’t really think there is anything the G1000 does the Avidyne doesn’t, except by integrating the 430 into the G1000 in contrast to the separate units with the Avidyne - the former is a neater piece of kit. I understand it is still the case that the G1000 can only be repaired by authorised Garmin service agents - so this could be a significant issue if there is not one close to hand. On the other hand the Avidyne units are I gather usually returned to the factory which is also a potential issue. For serious IFR flying (not relevant at this stage) I like the redundancy of the G1000 (you can swap the PDF to the MDF if one screen fails) - you cannot do this with the Avidyne. However, these issues aside both pieces of kit are excellent and will spoil a new PPL. In due course both avionics stacks are up to the job of serious IFR and work equally as well for that purpose.
Personally, if I were in the market for a Cirrus I would find it very difficult not to buy the Perspective with the G1000. This has a host of features which even for VFR flying are really useful (and not part of the G1000 fit in the Diamond). For serious IFR there are significant safety benefits - dual electronic gyros, keypad FMS, and the auto level.
The KAP140 in the Diamond is not great. I suspect there are some reliability issues and it is temperamental in turbulence. The Cirrus A/P is a better piece of kit and the Garmin autopilot if fitted significantly better still.
Touring
As I said earlier the Diamond flies very pleasantly but is as lack lustre as any other training aircraft. The handling is pleasant enough and the stick is not an issue. That said it is far better with the Lycoming or the new 2L Thielert. (I appreciate your friend is interested in the Lycoming). Everyone says the side stick on the Cirrus is not an issue - I would agree. Whilst I have a fair few hours, I had not flown a side stick before (only a yoke and stick). I was happy to make the first landing after 15 minutes local fly.
The Cirrus is all together a better touring aircraft once you are comfortable with it. However, for the reasons I have said earlier care would need to be taken to mentor a new PPL for some time to ensure he is really comfortable with the aircraft, and that process might taken significantly longer than with the Diamond. It is a better tourer because it is more comfortable, rarely struggles for performance, feels solid and will ride out turbulence with more aplomb and of course, is significantly quicker.
Parachute
Well, there are plenty of lies, damn lies and ill informed views about the chute. Fact is you hope you never need it, but fact is if you do the evidence so far would suggest it could save your life. Given the afore you have to make your own mind up whether that is a factor in the decision making process, Some will say you will almost certainly never need the chute and some will say it encourages you to take chances you would not otherwise.
Reliability
I have found both aircraft reliable – you are purchasing into almost certainly a low hour and low time aircraft. How well they will stand the test of time is another matter – but I suspect there will not be much between them because after all most of the components are not specific to the aircraft manufacturer but are assemblages of parts from the same part bins.
There are some specific issues with both aircraft, the list isn’t too long, but I am not going to roll it out here, not least because none of the issues would in my view be persuasive in terms of which aircraft you buy.
Good luck to you and your friend.