What would the pros and cons of both be? Also personal opinions on each?
To be fair, you must give us more specifics on each revolver. Photos would be very good, but you may not have access to the revolvers for them. With both guns, manufacturer/importer, date code, serial number, any maker marks, proofmarks, etc., are very important insofar as determining what they actually are.
An engraved brass frame 1851 navy
IMO, those guns are cheaper obscure manufacturer Italian revolvers made for eye candy: bling. As has been stated, if you want it for a shooter, a brass frame is not the way to go. If you intend to shoot fairly stout .36 cal loads (23-25 grains BP), the revolver will not last long as the steel cylinder will imprint the cylinder ratchet teeth into the brass recoil shield of the frame, which will result in much cylinder endplay, causing the barrel/cylinder gap to deviate a bunch. If you shoot it, stay below 15 grains BP and it will last a long time. Having said that, part of the fun shooting BP revolvers is the big "boom" and the smoke when you touch it off, and that's why I only shoot steel frame revolvers.
Connecticut Valley Arms was an importer of various Italian manufacturers early on in the rush to sell BP revolvers. As was stated, the Walker is a very large revolver (4 lbs. 9 oz.) and has a large tendency to drop the load-lever/rammer on almost every shot, which prevents the cylinder from rotating to the next shot. Their are cures for that, but it is something to take into consideration.
For $300, I would definitely go with the Walker, but you must understand that replacement parts are either not available, or at best, slim pickings, depending upon the manufacturer.
Good luck!
Regards,
Jim