a very good low noise power supply can indeed approach and sometimes better batteries IMO. batteries are easier to do it with for sure. how do you address charging John? BTW I am in the middle of sending you a PM about this over at DIYA
I have tried to order a batch of chargers from both these companies but they insist on either using UPS or Fedex (& the associated rates > $100) or USPS without any insurance protection & I'm not willing to risk hundreds of dollars. Jeez, talk about not wanting to do business .
I have used discarded mobile phone chargers (< 3.6V output) but they don't run off automatically & so you run the risk of overcharging the batteries which will shorten their lifetime. I forgot & left one on overnight - no fire, no explosion but the battery read 5.?V in the morning - I discharged it down to 3.6V but suspect it's robustness. I also would not have liked the consequences of connecting this to the Hiface with chips expecting 3.3V (up to 4.0V max) - it would possibly have killed it.
So this is a cautionary way of doing it until a suitable solution is found or I develop something.