JWD, I recently did exactly what you're talking about. I've been thinking about it for a while and even e-mailed back and forth with Hans about a metal bridge that would fit the rosewood X-170 base. Of course, that's not easy since the X-170 base posts are on 3-inch centers, and finding a replacement bridge is next to impossible. I looked at the bridges on Stewart-MacDonald's site, but was a little leery.
Then one day while I was prowling around eBay, I came across a guy who was selling a Stew-Mac bridge, new, in an up-opened package, for a very reasonable opening bid. I e-mailed him and asked him if he could tell me the catalog number of the bridge. He couldn't, but sent me a link to the S-M catalog and said "this is probably the current replacement", but that his was older and probably not Chinese-made. So I bid and would up winning the auction for $25.00.
The bridge came, and sure enough it was still sealed in the packaging. I opened it and it turned out to be a Gotoh bridge and a very nice piece.
It took about 10 minutes of sanding to get the base to match the contour of my x-170. I pre-set the intonation to resemble the rosewood bridge, centered the new bridge over the soundpost, and strung it up.
Plugged the guitar in and hit a chord. WOW!!!!!!!! Everything I had hoped for. Louder, brighter, cleaner, crisper, and with sustain that goes until Tuesday!
Since then I've spent some time setting the intonation more accurately, and playing the snot out of it. I'm in love with my guitar. I put the rosewood bridge in a plastic bag and stuck it in the compartment of the case where it will spend the rest of it days, or at least as long as I own the guitar.
Now, your mileage may vary. I don't know if the bridges that Stew-Mac sells today are the same as I have or not. You also may not like the sound after you make the conversion. But that's my experience. Something I've wanted to try; the planets aligned so that I got a good bridge, and I'm as happy as a clam.
Let us know what you decide and how you make out.
Jeff