Hi frank,
both products work well, but you have to know the limitations that each have.
Sand is great but is a little aggressive at times dependent on the media and supply pressure. Too close to the skin and you can heavily pit it yet to far and you may as well park it next to the beach on a windy day for the same result. Don't be tempted to reuse the media unless you have cleaned it well and consider that sand will get into everything and good ppe is required. Clean up is a pain.
Soda has a lot of the same properties as sand but the clean up can be a bit easier as it can be hose down to get rid of the remaining media inside the structure.
In both cases ppe is paramount. Masking down work areas and delicate wiring and fuel systems on the motor needs special attention. IM me and I can point in direction of some possible suppliers who would be able to give prices and coverage
Cheers ric