I have the D1, I have the X.
X has better reception, there's no doubt about that. The reception is better than the Droid, and my Droid has a Froyo baseband. Battery life is good, especially for it being a big phone.
Call quality is better. I will try to always get a phone with decent noise cancellation from now on. Ppl on the other end wonder if I'm in the bathroom...lol
There is a GPS or phone sleep bug on the X where something may make your phone Running % be high or go to 100% even with the screen off and the app closed. Froyo fixes it....It turned out to be using a GPS app and leaving GPS on after the app closed, but there could be other apps doing the same thing. Spare Parts is a good app to see whats going on under the hood.
I constantly get 1 day and some hours outta my X, in a good reception area. (Home is good, work is bad). I needed to use SetCPU, good voltage kernels for the same numbers on my Droid with a kernel running 1Ghz or more. At work, it lasts about 6-8 hours. (Some areas at my desk I get No Service)
I dont really miss custom ROMs cuz I personally started using stock ROMs right before the X was released. I will take root and the great root apps thats available. If the custom recovery holds up on the X, thats even better.
I still have my Droid IF I wanna play with custom ROMs. I think the X is better cuz it has better phone functions, reception was the key for me keeping it... cuz the Droid has very good reception. But if u want a completely customizable phone, the Droid is where its at.