In our company as well in KLM there is enough experience with mixed-flying.
The 800 looks like an 737, but handles differently, its heavier, longer and has different performance.
It is perhaps a simple comparison, but flying the 200 is like having an analogue wrist-watch, while flying the 800 is like having a digital one...
I like flying the 800 very much especially flying PFD&ND, we had some experience with EFIS MAP during certification in Seattle but I find it a waste. We and KLM are mixing 300(EFIS/MAP) with 800 (PFD/ND) and it is possible as long as you are very, very carefull, Good luck...