having been able to compare both phones as i have had them boot rooted and tinkered with, they are both great.
I sold my x and jumped ship more as a testament to my hatred of what motorola had done than the actual droid x itself. It was a solid device and I liked it.
I have had the fascinate now and its rooted, de-binged, and over clocked with the voodoo lagfix. While its only 2.1 u1 at the moment and awaiting froyo, its a beast. Trying to compare a stock fascinate using touchwiz(or any galaxy s phone) to one using adw or lp and voodoo oc kernel is a terrible, terrible comparison.
The fascinate flies and is fantastic with video and gaming. The build quality is better on the x but the fasinate isnt garbage either. I have found battery life to be virtually equal now that the battery is broken in as with equal use at the end of the day I was always at 60% on my x and im at about the same on my sf.
call quality was better on the x, but in my experience anway the sf's isnt that much worse or as bad as many have complained about. Data is over 3g is just as fast and Ive had no issues loosing 3g.
GPS is bad, theres no hiding that and if you need gps a lot than the sf is not for you (we ll see if it gets updated for that at some point)
Wifi, again in my experience, is much better on the sf. On verizon 25/15 internet at my house by the router the x topped out at 18 up and the sf pulls the full 25 down. About 50 feet from the router the x was anywhere from 8-10 down and the sf is still 12-14 down.
Obviously everyone is going to be a fanboy/fangirl for their own device and bash whatever they don't own, but at least verizon has a lot of great android choices. Unless motorola (and we ll see about htc) reverses its policy towards attempting to lockdown the device I won't support them, and I'll look for an alternative.
Samsung is slow to update their phones which stinks, but hopefully soon we ll have froyo for the galaxy s phones and really be able to compare the x and sf more closely (i will say I'll like the sf on 2.2's chances

)
And to speculate on gingerbread for any phone at this point is pissing into the wind. Yes the dx is the flagship of motorola at the moment (sorry d2) but as soon as their new monster phone comes out, its anyone guess to what extent they make an effort to get future updates out. Samsung who knows, but with the rate I switch phones, it prolly wont matter.
Ok, I'm done. Everyone enjoy their phones and have a great day.