In general the 7.62x25 from a pistol will have slightly less energy than a .357mag/sig, it will be around 200fps faster, have about half the grain weight, penetrate better, shoot flatter and not expand as much. I have read of people getting good results from bullets made for the .32acp.
If you're after a homebrew Five-Seven look into the .22 Reed Express which is a 7.62x25 necked down to .22 and there are drop-in barrels available.
Personally I find the penetration of this cartridge to be one of its main selling points, along with the flat trajectory, but only with the larger .30cal bullet. The .22 Reed Express and .223 Timbs variants definately have their place in defense or target shooting but I don't feel they're nearly as versatile as the larger bullet original. There is more than enough velocity and mass to work with to produce some excellent fragmenting or expanding bullets in addition to the currently available fmj offerings.
I'd love to see a modern fullsized doublestack combat pistol chambering the 7.62x25 and a folding stocked carbine in the same caliber using the same mags. I feel the carbine would outclass all other pistol caliber carbines in terms of outright versatility and applicability to urban defense while the pistol would be much more handy and controlable than those based on the longer and more powerful .30 carbine. The overall cartridge length is very close to that of the 10mm, and the 9mm wide case ought to feed from a 10mm magazine without too much trouble, as many .40sw magazines will reliably feed 9x19mm. It would not be hard to pull off.
In case you haven't noticed I am a huge fan of this cartridge. It has successfully unthroned the mighty .357magnum in my eyes, previously my perrenial favorite. If I just absolutely couldn't ever have the 7.62x25, the .357sig would be an acceptable alternative, but the two are so totally different it isn't the same thing at all.
Everybody and his brother makes a 1911 or AR clone, nobody is making the 7.62x25 combat pistol, though the Russians *almost* did before copping out and going with 9x19mm for their new service sidearm. I am not sure if this says more about the lack of innovation rampant amongst gun manufacturers these days, or about the sameness and dull taste on the demand side.