I think it is. Do you have any vacation time planned over the holidays? It's ideal to switch at a time when you'll be around and do a fair amount of testing if at all possible. Especially going from Prozinc to either Lantus or Levemir. They behave quite differently so you'll want to keep an eye on Phoebe's numbers.
If you don't have vacation time coming, then you can still make it work, and the folks on the L/L forum can help you get ready for that.
Before you decide, it would be probably be helpful to read the stickies over there. They have a TON of information and run the forum a bit differently than we do in our smaller forum over here, so a little time to lurk and read and become familiar can help. (if you haven't already done that).
Also, before you decide - when was the last time Phoebe was at the vet and had a blood panel and exam done? If it's been awhile, it's worth ruling out some other health issue as a possible cause of these numbers.