Question for Saiga 12 owners...?

I seriously plan to buy an Izmash Saiga 12 very soon. I know various companys like alliance armament make 20 round drums for the Saiga, and I wanted to know: How reliable are they? If they are fussy, jam or break I might as well buy another 10 round box mag for 20% the price. Any input would be greatly appreciated. I learned my lesson after paying dearly for a 75 round ak drum that's really best-suited for display only.