>>I held a S&W 686 with 4 inch barrel... and loved it. It felt great in my hand, not too heavy at all. I also loved its look. ... I just feel so drawn to the 4 in. as it feels and looks better, plus my wife likes it better as well. I WANT the 4 in barrel<<

It couldn't be more obvious to me. Get the 4" bbl! The above is far and away the most important part of this decision. I'll provide some added info below for you, but it's not needed.

You clearly like the 4" more, you'll probably shoot it more often because of that as well. Get it.

>>is if there is a real, discernible difference in accuracy and recoil, especially with the .357 rounds.<<

I can't definitively comment on the accuracy. One can shoot either more than well enough for accuracy.

>>Some have said you can shoot the 686 all day long with .357 rounds, others have said they still come away with sore hands after a few cylinders of shooting them.<<

I think that will mostly be personal preference. Some will be more recoil sensative than others. Frankly, I wouldn't bother shooting much .357 regardless. Some do like to, meh.

>>Also, how about the .357 rounds reaching full potential through a 4 in. barrel? I understand that through small barrels the .357 round is not much better than .38. Is the 4 inch barrel going to be adequate?<<

The 4" will affect a 38 the same way it affects a .357, in large part. Regardless, either round is far more than enough power, and many make a good case against the .357 for self defense due to noise, muzzle blast, recoil, etc.

>>Another question. What about the 6 vs. 7 shot cylinder? Other than getting an extra round, is there any advantage or disadvantage?<<

Only other advantage is the application. The common gun games won't allow >6 rounds, practically. I'd get the 6-shot for all-purpose, but as with most things gun it's going to come down to personal preference.

>>I saw on the S&W website specs that the 7 shot was actually a tad lighter. I would have thought the cylinder having a 7 round capacity would make it heavier. How is this?<<

The cylinders are the same except for the holes and flutes. More holes and flutes = less steel.

>>As much as I like and want the 4 in.<<

There's your clear answer. The other "facts" don't matter nearly as much as this statement.

>>I would go with the 6 inch if it is going to have a FACTUAL, NOTICEABLE advantage over the 4 in. Any help here will be appreciated.<<

Personally I don't notice any difference between the two *after* they go bang. The perceived recoil difference just isn't there for me. Maybe it would show up on a timer in shot recovery or transitioning.

There is plenty of difference before the gun goes bang, though. And all of those differences have me preferring the 4", too.