There hasn't been any rain since my install - so I can't really answer that question. On the voom forum, there have definitely been some complaints about that issue - however, in most cases, voom did a free exchange for a bigger dish (18" to 24") that seemed to solve the problem. If I have rain issues, that's definitely something I'll request.
The picture quality is phenomenal for HD - every bit as good as I was accustomed to on TWC. I think the SD channels on VOOM look noticeably better than they did on TWC (TNT, ESPN, etc).
I got Voom for the HD programming, so I'm not at all worried about SD channels like HGTV, SciFi or whatever - but I know they matter a lot to some people. Voom knows this and I'm sure they'll add anything that's glaring.
As far as cost - I'm sure it will vary by what you need. It's cheaper for me to Voom. $39.90 + $9.50 lease for 1 receiver. Digital cable for one receiver at TWC is $55.95. And with Voom, I get a TON more HD.
WorldsportHD, ESPN-HD, RaveHD, UltraHD, BravoHD, GalleryHD are the channels I'm most excited about that TWC doesn't have (probably in that order). Of course, there's DiscoveryHD, reports of TNT-HD when it comes out, and the locals - PBS, CBS, ABC, NBC, FOX.
If you're into premium channels (which I'm not really) - Voom is REALLY the way to go. With HBOHD (east and west), ShowtimeHD (E&W), CinemaxHD (E&W), StarzHD, EncoreHD, TMC-HD - that package is $79.90/mo. I'll stron gly consider it when they release their HD-DVR.
Speaking of their HD-DVR, it's going to be out of control. 2 Satellite Tuners + 2 OTA tuners will allow you to record any two HD shows at a time. It will also work as a house-media-server, connecting to other receivers throughout the house (and you can watch any shows recorded on the hard drive on any remote receiver, plus schedule recordings from those locations, or start a show on one TV, pause it and finish watching it on a different one!!!!!!!). I can't wait!!!
And the best part is - just like TWC - no equipment to buy, no installation charges (promotion), and no contract.