Well now the dust has settled, I'll join the fray and - quelle surprise - actually attempt to answer the questions Jacko has asked.
And these are just the personal views of an old (not very bold) QHI
In theory, I don't see how the change should have any effect on the output numbers game. With the best will in the world, flying training (statisically) is a sausage machine. If you have x number of students, y number of instructors and z number of airframes/flying hours - the result should be the same - and those numbers ain't going to change.
Immediate advantages that spring to mind are primarily for the staff. With the "parallel" rather than "series" approach, all Squirrel staff will fly all exercises. One remembers when one was a Gazelle basic QHI, the joy of sending a baby Bloggs first solo before lunch, and teaching a more senior Bloggs to fly under wires after lunch. Variety keeps the QHI sharp - over-specialisation may (and I strongly underline may) lead to complacency and a blinkered approach, and a possibly reduced awareness of "how the other half lives". And of course being a Jack-of-all-trades is what we want our young helicopteristes to aspire to. No demo by an instructor is more accurately reproduced than the instructor's behaviour on the ground!
It may also be good for baby Bloggs (see above) to share a crewroom with senior Bloggs - much is learnt IMHO from crewroom osmosis.
(And it halves the amount of night flying and IF that 705 have to do!)
Disadvantages - few that I can think of. The much trumpeted "exposure to other service cultures" seems to me to be a bit cosmetic. 705 have "Shareholders" instead of Met Brief, and have a Splot. And I think 660 have a Sqn Sgt Major! The studes all live together and soon (very soon) will fight together - I don't think a lack of exposure to 660 or 705 will hurt in any way.
So on balance - possible advantages overall, but it's a bit close to call. So why not give it a try, and see if it does make a difference - I see little that could be lost.