Hardware wise, the hummingbird has the best graphics capability compared to the Snapdragon Adreno or the Omap PowerVR chip but the processing capability is the slowest of the three. All in all, as time goes on, more apps are relying on graphics speed, not really CPU speed anymore from what I've seen in the market.
The Hummingbird uses a Power VR chip too, its just the latest and best version: the 540. The Droid, Droid 2 and X uses the 530. The one in the X (and maybe the Droid 2) is clocked higher, so it performs a lil better than the one in the Droid.
It gets confusing cuz the Hummingbird is the name for the whole system on a chip (SoC), same for the Snapdragon. The OMAP...it doesnt have a name like the other 2. It uses the name of the cpu.
I wont even mention the Adreno.....lol The Snapdragon needs to upgrade their gpu chip for the next version of the Snapdragon.
And it was discovered its not the slowest cpu. It has a lag/stall issue that slows it down:
http://androidandme.com/2010/07/news/droid-x-vs-galaxy-s-and-more-with-quadrant-professional/
Read the I/O part of the test. And look at the cpu part of the test. Will Samsung issue an official fix for that I/O issue, who knows. Folks at MoDaCo found a fix/hack, but u need to be rooted to use it.
And I agree 4" is the sweet spot. I'm happy with the X size, but I feel 4" will lure more ppl in that want to try something bigger than the Droid and Inc.
Now...some things I want on my X that the Samsung phones have:
That gpu, the TV Out, TouchWiz, I heard the audio on the Samsung phones are amazing.