I think that selecting UI2 shouldn't even be an option for install. It seems that too many are reporting problems with it, so it would make sense to default to UI1 and allow the user to try UI2 after a successful install.
I tend to agree. UI2 places many more demands on your graphics card/chipset and this can cause enormous problems if you have no experience with either Pluto or lmce. I think choosing UI1 initially is a good idea and having this the default would also be sensible.