To answer the OPs question (assuming that If was supposed to be an Is), yes, many, many folks use OTAP to program APX radios.
What you'll need at a bare minimum is an APX radio with the OTAP flashcode option, a trunked or conventional system with IV&D, a hardware Advanced System Key (with the OTAP privilege enabled) to match your system, and of course CPS.
When using standalone OTAP, CPS has no choice but to write the entire codeplug to the radio. The APX CPS Radio Management suite can overcome this limitation, because it ostensibly knows what is in the radio before you go to write it (by virtue of having previously read the radio and recorded the resulting data), and so can do a differential write, which only sends the parts of the codeplug that have changed.
The caveat to using Radio Management is that if you make any modifications to the radio codeplug outside of RM, you won't be able to initiate a write-only job to the radio without a read job into RM, to re-establish RM's baseline understanding of what is in the radio (it can detect that the radio was written more recently than what RM remembers).
On the plus side, if you have a current CPS subscription you can also download the CPS RM suite, which includes 100 free radio licenses for RM. That way, you can play around with both standalone CPS, and the CPS RM suite, to determine which (if either) would be suitable for your operation.
RM for a handful of radios should run on any computer capable of handling plain old CPS. If you wanted to manage a fleet of radios more than the 100 you get for free with the RM download, then you'd want a dedicated server (or two), and the more cores/RAM the said servers have, the faster your RM jobs will be processed.
Since you can only use OTAP in the presence of a system, speaking to your system guy(s)/gal(s) and your local Motorola rep would probably be good avenues for further understanding beyond what's been presented here.