I can't comment on Touchdown or corporate stuff, but I made the switch from OG Droid to X. I haven't regretted the decision at all.
Things I noticed:
* It took me a day or two to get used to the rearranged home/menu/back/search buttons. That one tripped me up quite a bit in the beginning.
* I rather like the streamlined Blur overlay for most situations. It's clean enough looking and not too intrusive, and the Motorola widgets are actually pretty useful.
* The integration with different account types is both reallly nice and really awful, depending on the account. For example: I like that I can link to picasa, photobucket, and facebook to upload pictures without an additional app. I like that there's a built in yahoo mail option that can link to a universal inbox that also shows other emails, text, and facebook messages. I loathe the fact that I can't view my picasa albums in my gallery like I could on my Droid. I'm annoyed that I can't see my gmail messages in the universal inbox using the gmail client, but instead have to setup my gmail as a separate IMAP account. I'm annoyed by the craptastic built in twitter functions.
* The huge screen is awesome, plain and simple. I've messed around with the Droid recently and it seems microscopic in comparison. The colors are a little washed out when compared to the Droid, though.
* The gallery is much better on the X. I hated the 3D gallery on the Droid.
* Maybe it's a mental thing, but the wifi on the X seems a little flaky compared to the Droid.
Those are the main things I can think of off hand that stuck out when I made the switch. Most of it is really good, both hardware and software-wise, but every now and then there seems to be a fumble. Hardly a deal breaker, but quirky. How it deals with your corporate stuff may be the more important deal breaker. You may wish to do a separate thread to see if someone else has dealt with a similar setup on their X.