Brake bleeding help...

[rhock99 at epix.net (Ryan H)]

I snapped off the bleeder valve last time I bled the brakes, thankfully it stayed closed.  But I plan on swapping pads/discs/lines in the near future, and was wondering - would a power brake bleeder eliminate the troubles I would have with trying to bleed the system?  How, and more importantly, how good do these work?  Worth it ($44)?  Thx!
The front calipers are fairly new, so I don't wanna have to replace them just cause I can't bleed one of them.