It's usually not recommended these days to be honest. With the electronic solenoids and high rates of fire there is a real chance of the marker icing up, even with the AS installed and causing major issues.
You're going to have to consult the manuals of the markers you're looking at to see what the manufacturers recommend. They should all be available online for viewing.
The only way I would do it would be with a Palmers reg on the gun to make sure liquid doesn't get deep into the gun. Technically if Smart Parts said it was okay than it should be fine but those had Max Flo regs that loved co2.
2000 Tropic Green CSVT #836/2150
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Palmers would certainly help but I would still check the manuals. I would imagine the BT would be more accepting of the usage then the Etek. But you never know which is why checking the manual is the best thing. Or contacting a rep even.