Very interesting question. I'm yet to look into this Calum - but I'll check and get back to you.

Edit: I just checked, apparently it's only about sexual attraction and competition that triggers the T-increase - so while I'm not sure if studies exist, it'll likely be the case for homosexual men too. Only one way to find out - a T-increase is very "feelable" - so best to try it out via experimentation and observation.