Hi Fran,
if you're happy with your SGM180 stick with them.
I've got at least half a dozen of the commercial sets including the latest Sonivox set & I've got Papelmedia (soundfonts only)not this new thing.

What I'm doing with mine is mix n matching ie I'm using an sgm128 piano, provitamin drum kit ( xg mapped ) Papelmedia choirs, etc etc as i find a more suitable sound amongst my various fonts, be it bass , strings whatever, I just replace the old sound with the new ( or I just create an additional bank to add it too). Even though I stick to the basic gm mapping ( piano 0, strings 48 etc etc I can still have many additional banks.

All the gm banks I've got have their good & bad sounding instruments.

best wishes
rikki