I've flown both the Thielert and L360 DA42's as well as the PA34 (II, III, IV and V). The PA34 is, in my opinion, a stable instrument flying platform that prepares a student reasonably well from a handling and capacity perspective compared to hand flying a B737 or A320 type during MCC/JOC. The DA42 is light by comparison and the high aspect-ratio wing gives it fairly forgiving but 'floaty' handling characteristics in the flare that are not typical of transport type aircraft. Another point to note with the DA42 is that it is not equipped with a conventional T/C and therefore it's not possible to practice unusual attitude recoveries in the traditional sense; with greater emphasis on recognition, prevention and/or recovery from upset conditions now being mandated by the regulators, I find the absence of this basic instrument surprising in an aircraft used for initial instrument rating training. As said, the G1000 is a nice piece of kit but quite unlike the EFIS you will find in a transport type - it's as much to do with the architecture and philosophy of the system as the presentation, in my opinion.
I don't think the lack of pitch levers on the Thielert engined -42 is of any concern unless you plan to fly other piston twins with prop/mixture controls. In that sense, the power levers are more akin to the thrust levers (or throttles in old money) on the types typically used for MCC but without the spool-up and larger pitching moment.
jamesgrainge
If you pass PPL no problem, ATPL exams no problem, why would you struggle with any other part of the ratings?
In fact many do, as although a PPL is a great foundation if the training is good, the CPL and multi-engine IR require a different skill set, greater capacity and application. Bear in mind as well that the ability to pass theoretical knowledge exams is no indicator of practical potential and some high achieving graduates do drop out of the practical phase. I would agree with parkfell's opinion in this regard.