*IF* the version of the OTA differs from 246 then Samuri will be on it - this we can be sure of! He has responded very quickly to new builds as they have appeared. Plus, given all the people who read this whom have already taken the plunge, well, know you will not be alone.
But if you looking for absolutes: wait for the OTA. It's what I'm having my wife do.
It is generally. Going from 905 > Leak is dead simple. Going from 246 > 248 (if this happens) is only a tiny bit more difficult. Sam has really done amazing things w/that batch file! He has gotten it down to being less risky than taking a leak (so to speak).
It won't provided you follow the instructions. Even then, unless you do something truly stupid the process is fairly idiot proof - I was skipping step 2 which is critical and didn't brick my phone!
Keep in mind there are 0 guarantees. You can have the OTA hit your phone and well.. if your phone loses power during the upgrade process, you're toast.
Lodmot, only you can decide what's right for you. I personally find it weird you keep posting here saying you want guarantees but want it and keep posting about it. You're on the fence it seems. Decide for yourself, feel good about it and be content. Yes it's scary, but if there is one thing you have seen now very clearly is that there is a fairly large community of folks here who are willing to help you if you decide to take the plunge.