If you're losing or gaining anything it's not going to be much.
I can't really tell from the picture if that SKS has a detachable mag, but it looks like it does, and in the case of an AWB you'll no longer be able to purchase them (unless you go through a private party, iirc).
It looks like they went with Tapco furniture, which is on the cheap side, but gets the job done. That means they may have also gone with a cheap red dot. Find out who makes it and let us know, that could easily be an extra hundred dollars on the gun, or maybe only twenty.
If the magazine isn't detachable, I've heard bad things about most of the high caps. iirc, you'll either want to stick with the stock ten rounders or I think one of the Tapco twenty rounders also work well.
<edit>
c3shooter: I haven't heard that before, but it sounds like a good idea. Thanks!