After thinking about it thoroughly, the cheapskate in me as won and I will just buy a phone capable of voice (ie. any phone out there $50 or below). I will continue to use the N810 for VoIP when I'm around WiFi, and re-direct calls to my mobile when I'm out and about. With a cheap pay-as-you-go plan (I'm assuming that one exists), I'll only need to top up every now and then as I RARELY will need to use my phone while away from my work or home.

The benefit is a lower cost (both phone and plan). The loss, is a phone that doubles as a toy and adds a tad more convenience (one less device to carry around -- the N810).

}:^)~

I know this is off-topic, but I'd just like to point this out for those that may be interested:

For those that are looking for a great canadian prepaid service, look no farther than your local 7-11 (yep, the convenience store). They offer prepaid plans with 25cent/min billing and all prepaid vouchers are good for 365 days before they expire! The major downside is that the service only works with phones that they sell (and the selection is limited).

I'm not sure what types of phones can be used with their service, but they're hands down the best prepaid service I've found yet.
http://speakout7eleven.ca/

EDIT:
I've just learned that Speakout wireless operates on the Rogers network, and at least one blog post confirms that you can swap the SIM into any rogers compatible phone. This is the best pay-as-you-go deal around for light use, and the phone options are much more pleasing than once thought.

There's also a promotion going on right now to get $20 off any of their six handsets if you purchase a $50 talktime voucher. If you get the cheapest handset, it'll cost $40.

This is an amazing deal for Canadians that only use their phone away from WiFi once and while (ie. me). I suspect you could plop the speakout SIM in the N900/N1 and reap the benefits of cheap pay-as-you-go when you're away from the house!

Good luck,
}:^)~