Have you installed his build yet?
No, but I'm downloading as I type this LOL. I just got Viper up and running recently though, so I think I'm going to run it for awhile so I have something to compare Calkulin's ROM to. I've been rooted for a few weeks now but I hadn't flashed a ROM until recently as I was waiting for them to mature a bit. I decided on ViperROM as that guy really knows his stuff and he's really involved in his ROM thread.
Regarding LOS, here's my experience so far. I've only had it happen twice since rooting three weeks ago, both on a custom kernel (LoStKernel), and both times I was in one-off locations that I rarely visit. I haven't had a single LOS anywhere else, which includes home or work or anywhere in between. I'm still open to the possibility that I would have gotten LOS in those two spots on the stock un-rooted kernel, but I'll never know for sure.
I also ran the stock pulled kernel for awhile with no LOS. That's always an option for you if you decide to go for it. Flash whatever you want to get rooted (may as well use LoStKernel since it's already in Calkulin's ROM), then CWM flash his ROM, then flash this
[KERNEL][ODIN] Stock Pulled Repacked with CWM5 to have a kernel pulled from an un-rooted phone. LOS seems to be a bug with how the phone handles a low signal / roaming environment, and something about recompiling the source code Samsung published increases the likelihood of a LOS event. But the stock pulled kernel is not based on that source, it was yanked off an unrooted phone and CWM was added to the initramfs. Chris41g recently added init.d support to that kernel so it will work with Calkulin's ROM.
If it just turns out to be a nightmare, there is a way to go back to completely stock and unrooted.
It's all up to you though of course. This phone runs just great stock as you know. I just like to tinker and tweak, and tinker and tweak some more, so I was willing to deal with the potential side effect, which has really been minimal if not a non-issue. YMMV of course.