Hey there,
Was basically in the same spot as you a few weeks ago, except I've got Cricket. I jumped right into using Helmi's ROM and it seems to be working great for me.
As far as the UIs of the different builds.. I think they are all pretty much the same. Of course you can install certain customizations from the kitchen.
SMS should work out of the box for you, however MMS sometimes does take a bit of tinkering. Since you're using verizon I'd suggest that you do not select either version of Arcsoft MMS that's in the kitchen - however PDAPhoneJunkie recommended me the old official VZW arcsoft cab and I have had the best luck with that. Check this post
http://forum.ppcgeeks.com/showthread.php?t=36184
As far as I know most people using Helmi's WM6 have working wifi. Pretty sure mine works.
Just remember one thing - keep your rom very light in the kitchen, don't add a bunch of garbage 'til after you've flashed the rom to the phone.
Good luck captain. Let us know how it turns out.