I don't for a second expect Fellaini to be a "non-factor" or a "downgrade" even, if he came here.
He would be a good addition, but there are a few others that I'd rather try and sign (Gundogan, Thiago, Strootman, possibly one of the Bender bros).
People shouldn't however use "Fellaini not fitting into our style" as an excuse.
First of all "our style" isn't our style anymore, Ferguson has retired and Moyes isn't the same person.
Second, even Moyes' style at Everton won't be the same as the one he'll use here.
For one thing Moyes never had any money to work with, and the talent of players at his disposal was significantly less than the amount of talent he has to work with here.
The way he set up at Everton was the best way to utilize what he had there, it would be foolish to think he won't adapt (and continue to adapt as he gains more experience) United's style of play and make it his own, only this time a style that's not "limited" by lack of funds and subsequently lack of talent.
I mean sure, we're no Monaco/PSG/City/Chelsea in terms of transfer movie available, but cash is available if the need arises, atleast that's what Ferguson told us and it was evident (atleast) last year when we almost signed Moura and Hazard for huge sums of money on top of other signings, not to mention we're bound to get rid of the debt sooner or later the way the Glazers are chipping away at it with all the deals.