Yes, they probably couldn't fix the damn turbo lag on the 1.3 90, so whether 5 or six gears makes no difference if you're stuck in first on that roundabout!
But seriously, don't let that put you off, the 1.9 Dynamic is a great car (read the thread about why you should buy a GP) and good value too.
If your car was built last year it might have the six speed gear box; I bought mine in Jan 2007 but it was obviously built some time before that and has 6 speed. Makes not a jot of difference to the performance AFAIK.
At least you had the option of choosing between the 90hp and 75hp models for a time.
In Denmark we never got the 90hp model (but that's most likely due to our very high tax on cars ).
I suspect there are no more 6 speeders around. When I ordered mine in January there were a few available but none were being built and the model was being replaced by the 75 BHP version. I think the 6 speed gearbox was discontinued in September. The gear ratios should be attached.