the S&W is a fine gun, the only thing cheap about it is that stupid plastic washer that holds the recoil rod in place. It is otherwise fairly solid. It is as accurate as the others. I put the buckmark, 22A, and ruger marks at a tie, and all 3 are all anyone needs unless doing serious competition. After these, plan to spend $1500+ for the next one (S&W 41, hammerli, etc).
I still use a mark II. My wife went a little oddball: she had a custom made cz kadet ($1k after all the work) that does quite well. She likes it but it has a lot of trigger takeup that most target shooters would cringe at. Once the slack is taken up it has a nice pull --- guess its glockish in that regard.
The buckmark can be a bit of a hassle to tap for a red dot. The back end of the gun has 2 screws that disassemble the pistol. If you mount forward of these, you have a front heavy result. If you mount to reuse them, you have to recalibrate the sight after you removed it to clean the gun. Can be an annoying issue. Speaking of how I know this, I have a 7 inch barrel (round version) buckmark with a rail already on it.... but you said 6 inches max....