I, too, happily use the SG20L for 16 ga RGL loads with 3/4 and 7/8 oz shot bars. Actual payloads are less. I tried about every 20 ga wad before coming around to the SG20L. Orange Dusters work just OK, occasional bloopers. I don't think I've ever had a blooper with the SG20L. It has a short shotcup, so I do get some leading.
I think you'll find there are other wads that work well in 16 ga RGLs: the DR16 and CB 16 ga wad are two. The former is best for lower payloads. The CB clone wad will work with a measured 7/8 oz drop. The RP OEM wads (R16 and SP16), of course, also work fine with higher payloads.
Sam