Is it safe to assume that this one will cause as many problems with its RF leakage as the others, and that ofcom will still do nothing about it?

I don't think 30 quid for a pair of 84Mbps homeplugs will render them irrelevant any time soon thank you very much. The only issue I have with them is their lifespan but I suppose if you leave them "always on", then 3 or four years out of an adaptor isn't bad. Obviously the 200Mbps ones are more expensive but I get plenty enough speed out of the 84's to make it not worth my while upgrading :)