The silent bug seems to be across all ROMs, even ones built from CyanogenMod source. Seems to be a physical phone problem (which I've never had, even once, with any of my 7 Eris's, strangely).
The 50% time without signal I don't even pay attention to any more. It doesn't seem to affect battery life, at all.
I use Ivan's Eris_Official 1.0.
Other people obsess about doing the airplane trick every bootup. I haven't found it to have ANY affect on battery, whatsoever. My phone sits overnight with mobile network off, uses 2% of battery or so, and the alarm wakes me up in the morning. Phone lasts all day. With or without the time without signal there.
There's a "trick" that people have posted about going into your phone's settings and changing "GSM (auto)" to "CDMA (auto)" but it's not really a fix, it's just some people being 100% confused. The setting is ALREADY at "CDMA (auto)" but they tell you to do something to make the program crash, and it defaults back to "GSM (auto)".
The "fix" doesn't actually do anything. I wouldn't worry about it.