The SGL is definitely a great deal for five bills (but not for the $800 regular price). One nice thing about the "factory" conversion is that you get a lot of nice AK-103 features that would otherwise be expensive, annoying, or labor intensive to do in a Saiga conversion at home--bayonet/accessory lugs, compatible handguard retainer, threaded front sight block, proper rivets, and a lack of the two holes in the receiver needed for the regular Saiga axis pins. For the last one, I'm not sure if Arsenal welds over those holes, or imports "semi-finished" guns with the trigger guard already moved forward.
None of these really affect the function of the gun, but for the current sale price they are nice to have basically thrown in.