OK, this is NOT intended to be a thread crap, so please don't take it as such, but here's my thoughts:
First off, I don't like Linksys stuff, but YMMV
Secondly, you CAN see differences in speed amoung cable modems, just as a good dialup modem can be faster than a bad one, the same is true of a cable modem.
Lastly, look around on eBay for cable modems. I got my Terayon TeraJet 210 (Which is generally considered the Fastest cable modem there is) for $51 plus shipping off eBay brand new.