Hi Geoff,
MSB/LSB is basically a process of "midi mapping" which lets you access any of the 64user/card performances or the single patch mode and lets you tie it up to your organ piston buttons. Roland organs have this feature, and I think Orla may too. However, I not too sure about the US1. There are a few of us on the forum that have Yamaha HX or EL90, and neither of those models have MSB/LSB, so I'm guessing you will be in the same boat as us. (unless someone can say otherwise) So, if that's the case, you have the option of using CF/SD cards to store only 16 registrations (accessible from your US1 piston buttons OR you can get the Events Processor box from midi solutions that can be programmed to give you access to ALL perfomance/patches on the Fantom. This is not always the best option if you intend to use your US1 along with the Fantom, but it depends how you want to use the whole set up.
If it's any use, have a quick look on the Fantom/TOIAB technical tips thread on this forum. It may help you decide which way you want to go.....I'm currently using CF/SD cards with my EL90, simply because I don't want to substitute any of the buttons on the EL dashboard to be used to access the Fantom - and this is how it is done with the midi processor box (eg. the sax button on the US1 could ne used to call up a user/card performance on the Fantom, a guitar button to call up another, a flute to call another etc.) Hopefully someone with US1 knowledge would be kind enough to let you know the midi spec of the US1 and confirm whether it does or doesn't do MSB/LSB. Hope this helps, and hope I haven't confused things more!
Regards
Nicola
P.S. the facility of having 16 sounds coming through to upper/lower/base pedals at one time, AND the ability to set "splits" anywhere you want makes this a perfect instrument for playing live... in fact, in my opinion, I think it is an "Arrangers" dream with the endless possibilities....