I think GM Studio removes the who publishers fee thing because Yoyo was manually converting games in co-operation with users up until this point... I'm not entirely sure though.
this
you pay for a pretty cheap license and then you can publish
Meh.
GM5 and GM6 aren't that much different to 7 or 8 apart from under-the-hood features, and a few gimmicks on the side like extensions packaging and syntax colors.
The most radical change is the Yoyo Games bullstuff and the reskin of the website but thats easy to ignore.
and there have been a couple GML overhauls