I've been looking around the web and the opinions are fairly evenly divided, with maybe a small majority not in favour of this (but not by much). It's so close in fact that I'm going to do a more detailed test. I'll do 200 mls with full beam and count the number of smidsys etc. and then 200 without full beam, and see what the results are.
As for the legality, I'm not really that sure. It might be reasonable to say that it's illegal to have your lights on full beam all the time in daylight - certainly the God awful HID things certainly shouldn't be, - But as a rider you have a duty to yourself and other road users to be visible. On page 107 of the Police rider's handbook to better motorcycling, when discussing the purpose of signals it has the sentence 'Only give a signal when another road user may benefit from it' highlighted. This is open to interpretation, I want other road users and pedestrians to see me. They are therefore, potentially, benefiting from my use of the signal: full beam.
Anybody who wonders about it may like to try it for themselves and see if they notice any difference - with the caveat that this may be viewed dimly by the police in your part of the World, (if you get busted by the police, it's on your head, not mine

). One things for sure, if you do try it, the World won't grind to a halt, you won't leave a trail of destruction in your wake, cagers won't be blinded, etc. etc.
A common sense approach to it's (high beam) use in traffic such as switching it off when it's obvious that it may cause a problem to someone else, is all that should really be needed.
It's interesting that riding your motorcycle with your headlights on full is positively encouraged in some places and not in others. Like filtering/lane splitting in different areas I guess.