I happen to have both the Incredible and the DX in my possession at this very moment. Why? The VZW rep assured me they could push Android 2.2 to me, which of course is not true. Since I'm a corp user, the security in 2.2 is essential. So after only two days of playing, I had them ship an Incredible to me and I've been using it for a couple of hours.
My initial thoughts after very limited use of both are the following:
The power adapter for the X is poorly designed. It's sideways such that it takes up two slots on a power strip. Good for wall outlets, bad for power strips. The Incredible did this better by elongating the piece vertically...good under both scenarios.
The micro-usb connector on the incredible looks flimsy and prone to break. I've seen this in earlier Blackberries (8830), and it's only a matter of time. The X is better.
The screen real estate on the X is amazing. I mean, really really amazing. After using the HTC for a few hours, I already miss the X.
That said, the keyboard on the X in landscape mode is almost too big. It's a little difficult to thumb-text. You almost want to lay it flat and type on it like a regular keyboard!
Both advertise 720p recording. That is perhaps technically true, but the size of the CCD is so small, don't expect actual HD. It's not bad though. Better than any other phone cam I've seen. This is true of both phones. The X has a 30-minute limit video recording, but you can start again. I was able to record all three 20-minute sets of my daughter's volleyball match as three separate files with loads of room to spare on my 16GB SDHC. (they won too, she's awesome!)
I'm kind of "meh" about the HDMI out. It's only for videos. You can't hook up the phone to a monitor and display the phone's screen which would have been awesome for training, or sharing a document in a presentation. The video transport buttons (play, pause, rr, ff, etc.) for the HDMI out completely suck too. There's no way to time-shift to a particular spot on the video. Like at 4:58 when my daughter gets a monster kill...you have to skip 30 sec-by-30 sec until you get there. Want the lobby scene in the Matrix? You'll die of old age getting there.
As far as GUIs go, I've heard that HTC Sense is immensely better than MotoBlur. I would disagree with that. I feel they are roughly the same, both with things done well and with shortcomings. I'd say Sense is a little more polished. Looking at the Car Panel / Car Dock application for both: Sense has nice icons and Blur is pretty feeble. But then again, the app doesn't rotate Horz in Sense, but does in Blur. In fact, I think the vehicle hardware implementation for the X is much better than the HTC.
I don't have a good sense of battery life for either device yet, except to say that both offer a lot of power-hungry eye candy that you'll want to play with.
Another thing about the battery on the X. I did something that in hindsight was kind of dumb and obvious, however I've read on the forums that I'm not the only one. Your pulling off all the plastic clings off of the X when you first get it, and in the battery bay (battery is not in place) is a black sticker that says "Pull"...so you do. Don't do that. It's for pulling the battery out because the geniuses at Moto couldn't figure out how to get the battery out any other way. I'd bet this is mostly tripping up Blackberry users who are used to seeing such a kludge.
Neither anywhere close to being as good as the BB when it comes to sound profiles. This is of course an OS thing not a hardware thing. The BB for example lets you specify that you don't want to bothered by anyone (no audible or vibrate notifications) unless it's one of the following people. There's probably an app I can get, but I haven't had the chance to look.
I keep looking the HTC trying to come up with more thoughts, but I should have left the office 20 minutes ago. I'm sure I had other complaints and praise.
Having said all of the above. I liked the X. If Motorola releases 2.2 before my evaluation period is over in 3 weeks, I'm sending the HTC back (hear that moto?). The Moto rep told me late-Sept/early-Oct. I've heard there are some problems with the Exchange integration and Active Sync. I don't know why it would be different for the DroidX vs. the Droid2.
This may not apply to you, but for others who are reading...I'm finding it a little difficult to separate Contacts and Calendar information between Exchange and GMail in the Android OS. In fact, that's why I came to this forum. Any advice would be helpful. (Sorry to hijack the thread).