I am not familiar with the Cabela's model but if it is basically the same as any other 629 Mountain Gun, the discounted price seems fair. I agree that the lock wouldn't worry me on a gun I planned to just use. I would disable it if it got to worrying me.
I am not the biggest fan of the Mountain Gun pattern for Magnums (and of 4-inch 44 Magnums in general), but the Mountain Guns are useful guns - just harder to shoot accurately than the standard models. If you get a chance to shoot both the Mountain Gun and the standard model side by side, do it. A half-box of 44 Magnums with both guns will tell you a lot.
My own choice in a lightweight model is the 44 Special. The Model 24/624 is essentially the same gun as the Mountain Gun, but without the blackpowder-chamfered cylinder and with a square-butt frame instead. I don't like shooting 44 Special in magnum-chambered guns, so that model is right up my alley. It puts out about all the power I can easily handle in that type of revolver. For the magnum round, I think I prefer the standard gun, in spite of the weight.