Generally in the Benko Gambit you are trying to generate play on the a and b files.
The Bg7 is a big help as often the Ra1 beomes uncomfortable. One set-up for white is to place pawns at a4 and b3, and a N at b5. If White can do this without a tactical mis-fortune he is doing okay. Black's counter-play is slowed down. One reason not play e6 in the Benko is that you want to keep your pawn structure as sound as possible, plus the idea is to play on the Q-side. White will try to react in the center. Black must act quickly to compensate for his pawn deficit, so if you waste time doing unnecessary things like e6, then you give White a chance to consolidate. I don't the Benko in tournaments, but I do play 1.d4 almost exclusively in tournaments. The Benko Gambit in the hands of an accomplished tactician is very scary to me. I don't decline the Benko , because you end up with the same kind of problems without the benefit of an extra pawn. I believe that your own results bear that out. I hope this is of help to you.
Is there a "Benko Gambit Group" on Chess.Com? There should be.
I have played the Benko Gambit a few times (including in a USCF tournament in the 1970's). I never had a problem with the Benko Gambit Declined. If someone declined it I played b5xc4 and immediately posted my rook on the half open QN file. I have never lost a Benko Gambit Declined.
The problem I have with the Benko Gambit Accepted is I am never quite certain where to post my knights. Am also reluctant to push up my QBP (unless of course I have managed to capture both White's NP and RP on the queenside). I have also been advised not to play e6. ChessGames.com has many Benko Gambit games to look at but all the players seem to have an array of different squares for their Rooks, the Queen and Knights. I need a little continuity. On Chess.com I have two Benko Gambit draws, one with White and one with Black in match play.