Well, 2005 is almost ten years old... that's like dog years when you consider what is coming out for VSTi type libraries!

But, maybe there's a slim chance there is an ARX slot under there... I would KILL to be able to put the ARX-03 Brass board in there. This is actually the first hardware keyboard with the tutti/split capability that Yamaha have added to the T5 so successfully.

Some of the other two ARX boards seems already in the BK-9 (I recognized some of the drum samples and Rhodes sounds), but the Brass board seems quite unique. Even if you HAD to program it with an iPad to get access to the tutti/divisi parameters, it would be worth every penny, IMO (and make Roland some extra bucks on the expansion boards that haven't sold all that well!)...

Overall, if you are in love with SRX cards, a Roland XV-5080 used module might be the way to go, with 4 slots or a used Fantom XR with 6 slots. You can get these under $700 or so, a lot less than an Integra7, LOL.