Vacuum Cleaners Discussions

Background:  I have a Simplicity canister S18 that I use for my hardwoods, other bare floors, and my accessory cleaning (stairs, edges, cobwebs, etc).  I also have a Kenmoor (panasonic) upright that recently broke down.  It was OK but I'm thinking I can do better.

So, I need a vacuum for carpets (i have 2 full floors of carpet and some on the middle floor). 
Definitely want a bag system
Definitely can't go over 500.00

I went to one of my local vac shops today and he showed me Riccar.  Seems like a pretty nice machine but I can't get one for my price range AND this particular store had some creepy sales stuff going on.  I just didn't feel 'good' there, ya know what I mean?  So, I went over to my other local vac shop (where I have made my prior purchases) and they showed me the Sanitaire line, and I liked the S677 the best.  it's 499.  The only thing is at the first store they did a demo for me and showed me that with the Sanitaire.....you suck up some rice, turn the vac off, and shake the vac and the rice falls out.  What is that supposed to mean?  Should I be concerened about this?

Oh, the second store (the one I like) carries Simplicity, so I could probably get a Riccar equivalent for my price range.  The sales guy did say the Sanitaire was better (at cleaning).

What do you guys think?

PS, I tried the Miele uprights and I thought the ergonomics was horrible.

thanks a bunch,
Jen