I used attn1's hack kit, and it's very easy but I never did try Bubby's method. Just be prepared to do plenty of reading as you'll probably need to tweak your phone a little. I adjusted my APN settings, flash a few radios and ROMs and had to find a GPS fix. It's all there, you just need to read a lot.
Benefits for me were getting SetCPU so I could underclock/overclock my phone to help save battery life. I went from 7:30am yesterday to midnight last night with 15% remaining... that's a record for my phone and my settings weren't that conservative. The ROMs have different features too, but as UltraDroid mentioned, it's a matter of preference. I went through a few already, and still want to try LeeDroid and a couple others.
There's probably a ton of other benefits that I haven't discovered yet, but I'd say if you like to tinker... then do it.