Two additional thoughts / ideas for you. Do make sure you put out a good sized bowl of water for them. Ours almost seem to drink more than they eat. They can spend a good 3-4 minutes at the bowl at a time.
The second thing is that Purina One is probably brilliant for your cat but one thing I learnt from another forum last year is that hedgehog mouths are relatively small so, if you can, try getting some kitten biscuit which is smaller and easier for the to handle. That said, it sounds like yours are tucking in happily!
