negative flaps--what speeds?

The manual for my 303 Mosquito is silent as to when the use of negative
flaps becomes beneficial during cruise. Any pointers as to what speeds are
associated with -1 and -2 flap positions? Any data on the LD benefits of
negative flaps at higher speeds?

I read Dick Johnson's flight eval (Aug '79) and my take away is that it
makes sense to go to -1 (4.6 degrees) at around 80 kts and that there's
little difference between -1 and -2. I also understood that article to say
that the speed of best LD could be increased by 5 kts by using -1. Is my
understanding on these two points correct? Dick says the weather was poor
and there was a lot of scatter in the data--does anyone have experience that
agrees/disagrees with Johnson's report?

Any help appreciated--specific to the 303 or regarding flap use during
cruise in general. Hey, I'm transitioning from a PW5 to a 15M and it's got
a lot of new thingies to get used to--retractable wheel, flaps, water,
LEGS!!! ;-)

Brent