Before investing in a T6 conversion I did a lot of research, here as a lurker
and all over the web, I also looked at various ones in the flesh, it's a lot of £££ to get it wrong. I had a T2 back in the day and have been caravanning for years, so not a newbie. As has rightly been said at the end of the day it's about what works for you but some things that came up may help.
My first issue was getting the right base cab, I wanted a T6 with low mileage and recent year, things like aircon less of a concern, but inbuilt heating yes please, again solar panels I can live without for now. Re the vexed insulation issue well I don't think there is a "right" answer. We had no problem with the T2 and none with the T6 neither being insulated, a front windscreen cover of the best quality, specifically tailored for the T6 seems more important and we invested in that. It's worked out just fine in cold, hot and soaking wet weather, so even if they offered to insulate it I would not bother.
So yes we went with a CK conversion sourcing it from Don Amott who sell them cheaper than CK directly
bulk purchasing I guess. It is one of the Monte Carlo conversions and I have no complaint at all, it even tows well and certainly makes a good use of the space available. The rock and roll bed takes a little technique to get back up but in all other respects we are happy with it and it's a total pleasure to drive.
I'm not quite convinced about the odd tyres it's come with but will only replace them when needed, the one issue but it's clearly a known with any conversion is the crappy headlights, they will be replaced!