Yeah, I wouldn't necessarily blame MM either, but I"m seeing the same behavior: whether in default GPS connection mode or through rfcomm, MM crashes (app shuts down) without notice but with regularity (=I can't run MM with GPS enabled for more than a few minutes without it crashing). Yes, the GPS unit could be really crappy (actually it probably is), but if a subsequent cat on the device gives good data, who are we to blame for crashes?

Not that I care about blame -- I'm more interested in what I can do to get the issue resolved.
In that spirit, I'll note that I haven't had much success with GPSsaver and crew. BT control panel/devices/ calls it an unknown profile.

So in answer to the "should I buy this?" question: heck, it's thirty bucks. Worst case, it don't work.
Is maemo-mapper a full-featured satellite navigation suite? No, but that's missing the point. You can use it for driving directions, but since it's free, it has access to a lot of other interesting things as well.