Heavy doesnt mean a lot of power necessarily. Heavy means more heatsinks, which allow for better heat dissapation. The capacitors inside could still be junk, you never really know untill the worst happens. Then again, if you invest in a UPS, you'll always be able to properly shut down your system, and let the UPS take the abuse.
The PSU I have, the one I reccomended, includes a little wattage gauge. At most, my system only uses 220 W of power idling. Now, if you're going nvidia and SLI, you'll see a higher wattage pull from the PSU. At least this way you can see what your psu is doing.
If you still go for the Rosewill, good luck. I have no experience with that brand and couldnt reccomend them.