Until someone comes up with a well informed answer (which this is not), my own personal statistics, having spent about equal time on T-Tail and 'conventional' tail aircraft, is that I've had worse tail iceing encounters with conventional tail aircraft than T-tail. In fact, I can't recall any significant tail iceing encounters at all on T-tail aircraft, but had a few wide eyed moments with conventional tail, particularly in your part of the world!
Regards,
Old Smokey