I also live in a humid environment; we either street-ride in storms or we seldom ride.
Although not directed to push the limits (never a wise approach to street riding), here are some tips from an expert, David L. Hough, author of "Proficient Motorcycling" (highly recommended book):
http://www.soundrider.com/current/1310/6Secrets-RainRiding.aspx
Regarding available traction, I could add that there is a huge difference between the effects of a light rain on dirty pavement and of a heavy storm that washes grime away.
Rather than assuming and over-estimating lack of traction, you can safely test how much is available for a particular condition by front-braking on a straight line.
If you have been practicing emergency braking, you could compare how much less skidding/sliding load the front patch can take on a wet surface.
For a rough approximation, you can assume that a lean of 45 degrees demands about the same lateral load than lifting the rear tire during braking (about 1 G), while average emergency braking (about 0.85 G) is equivalent to 40 degrees of leaning in a turn.
Note however, that the angle of lean is not directly proportional to lateral grip of the tires.
The proportion goes like this:
10 degrees: 0.18 G
20 degrees: 0.36 G
30 degrees: 0.58 G
40 degrees: 0.84 G
50 degrees: 1.19 G
60 degrees: 1.73 G
At extreme angles, forces escalate quickly and things may go out of control soon; hence, proper throttle control there becomes more critical.
"A motorcycle becomes potentially less stable as lean-angle increases......as we have seen, throttle-control plays a huge part in stability; the steeper you go, the better throttle control must be." - K. Code in ATOTW2
Consider tire's temperature as well: when raining, you can safely deflate the tires some (80~90%), so they reach proper temperature despite the cooling effect of the splashing water (but don't forget to increase pressure for dry riding).
This video shows what is possible on clean wet asphalt with street tires (only ones legal in Motogymkhana).
............And yes, practice and competition of Motogymkhana is in full swing in UK:
http://www.motogymkhana.org/
Thats what I'm talking about cheers;-)