Honestly, I wouldn't get either one of them, but of the two, the sears would be the better. The Sears model is deffinantly under powered and there's a good chance that the other is too. Neither one of them allow for use of the contact wheel which is very handy for more than hollow grinding. Dido on doing slack belt grinding; it can't be done with those machines. It looks like you could grind plunge lines with the Sears unit which you aren't going to be able to do with that first unit.
My advice is that you stick with files and sandpaper until you can put together enough money to get a good belt grinder. Look at Grizzly, Coote, KMG, and the other's out there. Tracy also sells plans and parts for building your own KMG clone. Personally, I think that both of those machines would be a waste of money.
Doug Lester