From my experience - I have been using the 2.0 drivers for the usb speedtouch modem and it IS better than then the 1.6 version. When I installed osx.2 the damned 1.6 just would not work at all. Following some easy editing advice for 1.6 to change its connection settings ( found somewhere in these forums) it would work but a message to the effect of "this application has been messed about with - do you want to fix or use it anyway" would always be displayed on startup. DONT select fix, just use it and 1.6 works with Jaguar.
Now 2.0 works fine, unaltered, more reliable etc.
The only kernel panics I get now is after sleep - i just dont put my mac to sleep anymore. I am presuming this is to do with the speedtouch drivers as 1.6 was a real dog on osx, now its more of a slight annoyance.
slightly of topic - Have you seen the amount of these modems selling on eBay. Dozens for sale every day. They suck. Constant advice is to ditch speedtouch and get an adsl modem/router to connect over ethernet. Does anyone else have any good recomendations for one of these. It will make life easy to connect my iMac, PC, and xbox (I am in the xbox live beta test)all at once to the internet.
I hope some of this helps.
oh, I think the 2.0 is osx only, os9 still uses 1.6.
MacR