Been running LPX modem for a couple of months now. No noticeable problems as far as I can tell.
Tried the GetRIL app as it was mentioned frequently in the XDA forum. Well, I flashed the Baseband I9100XXLPX manually (it was originally LPW with CM9 Resurrection Edition, if I remember correctly). Anyway, I wouldn't mess with this if it's not broken...