You can also use a floating ring cable to connect pedals to your modular, or just buy a pedal/effects unit with CV inputs/outputs (there are some really good ones - I have a Finegear Dust Collector that I use on everything, and it even came with LFOs for extra modulation). You don't necessarily need a special module in the rack to interface with pedals.
(Edit: this next part is now irrelevant, apparently. I was incorrect.) Honestly, I wasn't going to comment on oscillators (or the Behringer thing) since it's so personal, but if Brains can't have the new firmware, I also agree that a different Plaits clone that can do the new DX7 patch thing would notably expand your sonic palette in this rack.