Well you say you want versatility, but in what areas? From what i can tell you are after effects more than synths? Or not necessarily?
Last things first - B2003 - the shop has just reopened so maybe they haven't got all the options up yet, you certainly use to be able to buy all the synths separately, perhaps try emailing Ralf at rb(at)soniccore.com and see what he says.
i can recommend all the
space f stuff. BlackBox II comes with lots of synths, Echo35 (and amazing echo unit), SlapBack echo, Wax (wah unit), Dragon distortions, small mixers and lots more. If you don't want the synths you can get BlackBox II FX.
i also have the FAT Inserts which are great too. You can demo the mixers - i like the FB5 most and space f has just added a compressor which inserts into th mixer which i'm sure will sound great, but haven't bought it yet because i'm not sure where to spend my money either - i was thinking of getting DynaTube first to put my synths through - i think B2003 will sound great through this.
So many options, not enough money