thank you very much, I thought about something related to default values...

anyway, talking about the highest frequency, are there any drawbacks in setting it to 850? After months of use I can say it's very stable on my device (900 reboots very often).. thanks again

Well, I made some tests about new configuration... It seems ok with smart reflex about battery duration, anyway a min frequency of 250 Mhz gave me some problem ...

I use to tether my laptop via wi-fi (MobileHotSpot) using at the same time ssh and vnc server (x11vnc) on N900; well, this way wi-fi would disconnect often and no way to browse...

kernel-config limits 500 850

resolved all...

if this could result in battery drain when not needed, is there a way to switch lower speed aside from making a script?

Try QtMobileHotspot. I don't see how lowering min freq could affect adhoc connections.