Those are the ones we are using right now and break after some while because they are too old (the rolling rubber diaphragm is too brittle now and you get small cracks). The tables were resting on the rubber for 15 years and they've been not used floating for the last decade or more. The leakage is small so that you don't feel or hear it (soap water does not work when installed. Pressure loss is 15psi of a 3gal compressor within 1 hour or so, not big but enough to be annoying. We wouldn't care if we would have a constant high pressure air supply.
The price for the custom made legs are $ 9295, and for the standard 16" are $ 3710
We have "Pneumatic Vibration Isolators with Automatic Re-leveling". Height is 16in from top to bottom, so that would raise the table height by 2.5in which i think is not gonna be a problem as i'm pretty sure we can adjust the height of the horizontal beams of the frame and don't have other constraints except the clearance of the ion pump to the HEPA which should be fine. Do you have a price for the 16" ones? (S-2000A-416). The problem with the new legs could be how to mount the table to them. The mounting looks different (diameter, holes etc.)
We should probably consider using the newer version we have currently under the cryo table and the table in the richter lab. Using those would eliminate the need of working on our frame and those tables don't really care what legs they are using at the moment.
We have 4 Newport XL-A legs 13.5" high in the 40m. You can try them. You may have to replace some of the floating actuators but otherwise they should work just fine.