An SME 3009 will fit (I have two of those on Obsidian bases, as the SME was popular in professional use, if you could not afford the EPA 100.) I don't see any reason why any 9 inch arm would not work. Longer arms might fit, if they don't have a large mounting base or plate. Anything longer than 10 inches probably won't make it. At least with the original armboard, as it has a metal rim, which takes up real estate.
The EPA 100 is still the best arm you could put on that combo given the price. If you want to use 12 inch arms, OMA make slate plinths all the time for the SP10 that can accommodate any arm.
Jonathan
The EPA 100 is still the best arm you could put on that combo given the price. If you want to use 12 inch arms, OMA make slate plinths all the time for the SP10 that can accommodate any arm.
Jonathan