The new WASR's are showing up with threaded muzzles and removable brakes in standard AK 14x1 LH threads, and double stack mags. AIM Surplus and J&G Sales both have them, and I'm guessing this will be the standard for all new WASR's.
I have a Saiga .223 I did a conversion on. I also have a Romanian PSL, and just bought a WASR 10 underfolder. Honestly, the new WASR's are nice. It's got a chrome-lined barrel and a removable slant brake, which I'm replacing with an upsized AK-74 style brake. The magazine has some side to side wobble, but not anything that I anticipate being a problem. The rest of the build quality is excellent, with a Tapco G2 trigger group and tight-fitting parts. The action is very smooth for an AK. It's overall a rock solid gun.
Why did I buy the WASR if I already have a converted Saiga? One, the Saiga is the 20" variety, and two, the .223 version has an extremely heavy barrel. This combines to make a rifle that's long, unwieldy, and too heavy to shoot accurately standing up. Third is that .223 ammo is expensive, and fourth, that heavy barrel heats up like crazy. Because of these things, I have the rifle set up with a bipod and a Romanian PSL stock, rather than a standard AK configuration. It's a great hunting rifle, and a great target rifle, but it's not a good camping gun or a "for fun" gun. It's a tool with a specific purpose and range of use, but it's not practical in the assault rifle role. Had I gotten the 16" Saiga 7.62x39, it would be an entirely different story.
The WASR underfolder is thus my "fun" gun or woods gun. It's also potentially a truck gun, given its compact nature. Ultimately, I wanted an AK that's really an AK, not something that just works like one but is huge and heavy. The underfolding stock also appealed to me, since I could use it with the stock folded if I wanted. I got what I wanted: a solid, compact rifle that is comfortable to hold and carry, fires a respectable round, and didn't break my bank. I think I did well. I got pretty much what I wanted out of the Saiga, too: a smaller version of my PSL, suitable for smaller game.