I've flown both kites (but not the same size neck and neck so can not say about low end...).
You got to determine (IMO) which type of kite you want - as they are completely different.
Primadonna is an awesome C kite, with lots of bar pressure (as most has) and less depower but lots of turning power.
Mr Fantastic is much more a "flat" kite, with great hangtime and lots of depower.
I like both, but they are VERY different in nature
The best single kite I've ever flown, was Mr Fantastic in 8m2
It has such a huge windrange, and we could fly this kite in the same wind as others were on 11m2 kites, and it still has lots of upper end compared to other 8m2s.
THAT is an amazing kite.
But the other sizes dont have the same extreme range it seems - for some reason the 8m2 felt like both a 6m2 and a 10m2 and very very pleasant too...
Off the topic, I know, would just share what I experienced last year with the 8m2