I can't directly answer your question about Ooma since I don't have it. Phone Power VoIP service allows quite a number of VoIP adapters to be used, so I would suspect Ooma would too. But if you BYOD to Phone Power, not all features may be supported...for instance, not all adapters support a second cloned line (an included, free, service with Phone Power if you have the correct adapter). Hope this helps a little.
So not to question your decision to go with Ooma (certainty, the price is right), but I chose Phone Power for their excellent US based customer support. If I had this question with them, I would simply give them a call.
Whomever you do choose though, as long as your internet connection supports it (Phone Power has a little tester on their website that will evaluate the quality of VoIP calls from your location...run it three times for best results), I suspect that you will enjoy it. Sure wish I had made the switch sooner.