What functionality do you lose when moving to a custom rom vs. stock?
Basically most ROMs out there will remove Moto's BLUR. BLUR is basically how everything looks and motorola widgets, which arent many, but I particularly miss the social network one since its not a huge battery hog like the FB app. You will also lose Backup Assistant, lose the AWESOME camera app, FM radio capabilities, the lame VZW preloaded Bloatware(which i truly dont miss) and many other subtle but noticeable things. I dont remember them too well since i have not run Stock in ages. But there apps that aim to keep most of those functionalities in place while increasing performance. RubiX Blurry does this wonerfully and it was the ROM i was with the longest, but then switched to the more AOSP or "vanilla" ROMs (just more theme support there). There are ways to get some of the Blur apps back but it gets confusing.