Those air chambers stopped working probably a month or so after they were installed. IF the manufacturer recommends them, then you want engineered ones, not just a capped tube. Most valves can't close fast enough to need them. There are lost of valves that are decent, but I like the functionality of the Delta R10000 rough-in valve. Their 1700 series trim is decent and easily repaired, should it need it eventually. Based on the type of function you want, you can use any of three types: single handle pressure balanced; two handle, temperature and volume control; two handle, thermostatically controlled - one knob temp, second volume. The rough-in valve will accept any of those trim sets and functions - Delta sells the cartridge with the trim. The big box stores often sell it as a kit, but a plumbing supply will break that into two parts, the rough-in and the trim/cartridge. I've used Grohe and Delta, and found both to be quality. Some of it is style which determines which is chosen.