[Exeric]

One more thing. The FV-04VE1 HRV really wouldn't serve as a bathroom fan because it's only 40 cfm max. So scratch that idea. I'll just stick with a regular panasonic fan.

Also, to get good flow through ventilation to the bedrooms from the bathroom with all doors closed don't undercut the bathroom door and DO undercut the doors for each bedroom. That assumes direct return venting from bathroom to bedrooms. And always keep the bathroom door closed after bedtime.

edit:
Here's some numbers straight from the Panasonic whispergreen manual.
1000 sq home requires 33 cfm for house ventilation.
2000 ~ 43 cfm
3000 ~ 53 cfm

The equivalent power used on the 80 cfm model at those settings (30,40,50 cfm) is
30cfm ~ 3.8 watts
40cfm ~ 4.2
50cfm ~. 4.5

And the cost for the 80 cfm unit is 152$ at amazon, tax not included.
So I think even with the cost of putting in ducting between bathroom and bedrooms it is a good choice for a smaller home. There will be more heat content in the conditioned air for larger homes so as you get bigger volumes there are bigger returns for an HRV. That is what any person would need to weigh. But the amount of money and time you save going this route would give you a lot of options for increasing heat conservation through insulation and solar heating.