You know ive had mine for nearly a year and still not tried it multitimbrally (well I have, but not the way you are asking and I use reaper now not poobase but I know it can be done.)
A6 is great tho innit?
no matter what bells and whistles my TI had the sounds I coaxed from the A6 just slayed it, and now same with the CODE. As much as I hate being cliche its analog all the way baby!!
As far as soundsets go for the A6 there isnt much about really. I know you can download the banks from the people who contributed to the factory soundset (Rob Papen etc) which have a few extra sounds in but thats pretty much it.
Ive started to make some decent sounds on it so when I get to 128 ill throw a bank out for peeps.
tom