The first batch of S9 radios that were built was the good ones, they had the 1969 finals in them...I know the one I bought it didnt have any drift...
I ran mine in the truck for a couple years and then on the base for awhile, never had any drifting problems out of it...
But the Mosfet S9 radios, I heard guys talk about it been bad to drift, Ive got a local here who is a bout 30 miles North of me, and he runs the S9-175w radio, I dont no how much he uses it on SSB, but it sure sounds good running with his 21 Mosfet amp he runs with it..
The S9 I ran, it was the best talking radio think Id ever seen, and drove my amps really well also...
I know the RCI line of radios are solid on SSB talking...if your into talking on SSB mostly, Id go with the RCI radio...or just keep both radios and switch them out from time to time...