Ha, I didn't realise "roaming aggressiveness" was actually a setting, I've checked and it is!

It is, I always change that on our laptops in work.  Seems to be there on most Intel-based wifi cards.  Don't seem to have that setting on my phone though, so it really is a hardware and driver based thing.  You can either change it, or you can't. 

Does affect battery life a bit though, as it's checking more often when it's set to be more aggressive.

I've done that in the past but didn't notice much difference. Do you notice it working for you?

Yeah, on some of our laptops I see it jumping between APs when I'm walking down a corridor much quicker.

Well I guess I'll give it another try then.  I just remember being very disappointed the last time I tried it.