As far as USPSA goes no one uses a leather holster for them. Unless you already have a leather one and don't want to get something else, which apparently is the case here. I do in-fact see shooters using something like the Safariland cup challenge holsters, I think there are other companies that in a similar Kydex construction. These seem to work fine, not as fast as a race holster but better than a regular holster because you don't have to lift very much to draw. In other words, a regular leather holster, the muzzle has to be clear of the top of the holster before you can start to swing the gun in the direction of the target. This might sound like a little thing and to some it is but these competitions are all about speed.
OK. About your gun.
In USPSA (IPSC in the US) there is currently only 1 revolver division. You can use a race holster (or any other) as long as the trigger guard is covered. Iron sights and no porting so your model 10 is fine. However .... everyone ...and I mean literally every single revolver shooter in USPSA Revolver division uses an 8 shot revolver and moon clips. Can you do it with 6 shots and speed loaders? Yes. Will it be fun? No.
ICORE this is where you belong with this gun. For 6 shot revolvers there are two divisions, Classic and Limited 6. In either division you can use any holster as long as it passes a "jump" test and the trigger guard is covered.
Classic uses speed loaders
Limited 6 uses moon clips
This is not a recommendation but for ICORE L6 and Classic I use a Ghost holster on a DAA 2 pc belt. The Ghost holster is a race holster and (at least for me) it was a bit of a pain to get dialed in. For Classic I use a Safariland (two) triple cavity speed loader holders and I use Safariland comp 3 speed loaders but there are others.
For Limited 6 I use the same belt and holster but I have a moon clip holder made by Revo-Gear which is a little less expensive than the post types but you are probably looking at classic anyway.
ICORE allows any kind of aftermarket grips, thumb latches, Iron sights (or FO) and so forth.
The only other place I have first hand experience with is IDPA. Your gun will work there (6 shot, 4" barrel) you need a holster that is suitable for every day carry (leather will work here) and in the case of 38 special (minor power factor) you need speed loaders and single cavity speed loader holders that attach to the belt. Safariland makes another holster that looks like a traditional holster, I have one for IDPA. It is sort of like a molded plastic with a suede like lining material. It's inexpensive but the lining really grips the gun. I have tried everything within reason to get it to lose to no avail. I think if you went to a gun show and paid one of those guys to make a custom kydex holster (the while you wait vac-u-form guys) you would be better off than using that holster unless you want to get really radical trying to losen it up.
But to recap, I have seen shooters use the Kydex holster similar to the Safariland Cup Challenge and they work. In my opinion, if you have ICORE nearby then look no further.
. You'd get far more exercise going for a 30 minute walk. Even better would be daily 30 minute walks 
