I may be being really dense here but what do the phantom power modules actually do? If the mics can only handle a maximum of 9V are they just taking the 48V phantom power and stepping it down to 9V (with a 3 wire powering design)?
If so then I might as well make a 3 wire battery box as per poorlyconditioned and save myself some cash
Phantom power modules do two things: They give a low voltage (3 to 9V) to the electret elements, in 3-wire configuration. But also they provide a low impedance balanced output, using a transformer, or some transistor circuit. If you're doing long runs and/or you need to connect to an XLR mixer input, you want the phantom power. However, for us tapirs, we're probably running from our hat to our pocket, and we're probably running unbalanced lines anyway, so the batt. box is fine.
That said, I must admit that I love the convenience of plugging my AT853Rx XLR connectors into my UA5, turning on phantom power, and letting it roll. So, for open taping I would prefer the Phantom power, but for stealth, or for saving money!, batteries are the way to go.
Richard