Genuine inquiry, what's changed other than toe strap? And for my sake lets go back to year one. I think I can name some stuff, but I'd rather just hear it from a Union supporter.
Everything has been upgraded over the years except the heel loop and forward lean adjuster (which don't need to be).
Redesigned the ankle strap adjustment mechanism
Redesigned the ankle and toe ratchets
Redesigned the ankle strap (softer and lower profile)
Added multiple toe strap positions to the baseplate
They increased the size of the foam dampening pads
Added a padded footbed
Added a padded highback
They've pretty much addressed each of the gripes people have had over the years, including the toe strap. Outside of Flux's FTM cap (which I don't think they use anymore), Union's split strap is as good as any other that I've ridden.