I have the 225, and I'm basically happy with it, for what it is. It is
perfect for holding my home-made router table, and fine for holding
small pieces to drill or finish. Portability/storage is great.
However, it is just too small and unstable to use for any serious hand
planing or chiseling or sanding, for any large stock, or anything else
where you'll put any lateral pressure on it (It wants to tip unless I
stand on the little step, which gets pretty awkward sometimes).
Also, it is too low for any extended use - my lower back gets sore from
bending over (I'm about 6'1"). Four concrete blocks under the legs
would solve this problem, but then if you do hit/wiggle it enough, it
would fall off and be even worse. I've also thought of making a taller
table extension, but then I couldn't use the clamps or dog holes, and
my router table top is taller.
As for differences between the models, I was considering the 425, but
the 225 was in stock at my local Chase Pitkin, and I'd read several
reviews on Amazon about the boxes getting pretty smashed up during
shipping, so I bought local. I can't imagine the 425 would solve any
of the problems mentioned above - afaik, the only differences are in
the benchtop (extra block to extend the table and a clutch for the