A big thanks to Maslovsky for your suggesting the Symbol Wificards.
I started using the new card and WOW! what a difference in battery consumption.
The range is still the same - i.e. good - I haven't benchmarked by feet or meters, but the power consumption is extremely good.
Again by my benchmarks - the earlier Ambicom card that I have would just last one 'large soup' lunch at byrant park with the public wifi that they have out there and by the time I was fininshed so was the battery in my C750 (fully charged to begin with).
Now with the Symbol Spectrum Networker card, I have gone thru a soup and sandwich, or even one of those large tasty (but messy) Moeshe's Falafel and a coke and still have enough battery power to do some surfing and email checking (my company has blocked external emails) and then close down (nearly 30 mins spent at Byrant park all in all) otherwise I would get marked at office too long lunches.
Thats a big difference.