I have had some compatibility issues in the past between Valcom Access Modules and Bogen Amps because they work on different Voltages. It might work but if/when you talk to Either Tech Support in turns into finger pointing. I usually use a TAMB which is the Bogen version of their Telephone Access Module when connecting to a Bogen AMP which can do either FXS or FXO. If you use FXO then you need a 24v power supply.
As far as disconnect issues, I have had my share of disconnect problems on both FXS and FXO, so that is why I like a device that can do both so I have options when it comes time to implement.
In my experience though I have had better luck with FXO.