I guess I'm in the minority here as I always advise going with a .44M in a 2.5" configuration for a trail gun. My reasoning is as follows:
1-Most 'snub nose' .44's do not weigh much more than an an equal size .357M
2-You can down load a .44M to .357M ballistics but you cannot up load a .357 to .44 ballistics
3-The use of a .44M also allows you to use .44 specials. Buffalo Bore makes an outstanding 'heavy' .44 special load that should handle a Black Bear, if needed. Cor-Bon makes a great 165 gr HP in either a Mag or a Spl that is designed for SD, wouldn't make a bad trail either.
4-IMHO, a hot .357 out of a light weight revolver is harder to handle than a 'light' .44M load out of a Ruger Alaskan or a S&W Backpacker and you have the ability to shoot the 'heavy specials.
5-I don't worry about the lose of velocity in 2.5 vs 4", it is not enough to worry about.