"I read somewhere that the 7 shooters have some sort of timing problems and speed loaders are hard to come by."
HK, Longwitz , Maxifire (the rubber speedloaders) and I believe Safariland make 7-shooter speedloaders that fit the S&W 686Plus, the Taurus 7-shooter (don't remember the model number), and whatever other 7-shooters are out there.
7-shooters were made to emulate the 7-round capacity of the 1911's magazine. Of course in the 1911, you can also have a round in the chamber if you carry/store it that way.
Re: going out of time , well there are posts of all sorts on various forums about every conceivable topic. Actually, the more rounds are in the revolver cylinder, other things being about equal- and things are equal framewise/sizewise etc. between the 686 and the 686Plus - the shorter is the the trigger pull - the rounds are closer together in the cylinder. Best way to look at it is this : let's say the revolver cylinder has only TWO holes in it. So, you have to roll the cylinder all the way around 180 degress to get to the second round. That's a long trigger pull, and the point is that the greater momentum of the cylinder in such a long, fast roll is harder to stop than if it's a shorter-distance roll to the next round, and so the wear on the parts that move the cylinder around and stop it and hold it in precise alignment is greater. Owners have posted that the 627's trigger pull is relatively short for this reason.
Also, the cuts in the cylinder for the 7-shooter are IN BETWEEN the holes, whereas for the 686 6-shooter the cuts are right on top of the holes; many posters have stated that therefore the 7-shooter's cylinder is stronger.
Lastly, odd-round capacity (5 and 7 -shooters) revolvers are no different from even-capacity (6 and 8- shooters) revolvers. Personally, I'd rather have more rounds than less - speedloaders are not really that fast except for people like Miculek.. Some traditionalists prefer 6-shooters because of..well... tradition.
Anyway, good luck on whatever S&W you eventually get, 686 or 627 or whatever. Either is worthy of being fondled.