Indeed white did seem to gain an edge in Longson-Knott, 4NCL 2004 although the positions are still far from easy to handle. In general though Knott does seem to be the man for 6...Nc6 and has a good score with it. Indeed GMs Chandler and Gallagher have opted for the Tromp to avoid his Winawer in recent years...

Another idea for White: 1.e4 e6 2.d4 d5 3.Nc3 Bb4 4.e5 c5 5.a3 Bxc3 6.bxc3 Nc6 7.Nf3 Qa5 8.Bd2 and now after 8...Qa4 or 8....Nge7, White can play the modern move 9.Qb1!?
The move has many good sides: after developping with Nf3, White has no immediate fighting move on kingside (Qg4,...) but there are some targets on queenside (b7,king after long castling) ; Black doesn't win the d4 pawn as in Kasparov's gambit line (with Qa4) ; White can support center with c2-c3 without exchanging queens if Black plays cxd4.
On ChessBase online-database there are only 3 games after 8...Nge7 9.Qb1 and among them Short-Dolmatov,1995 ; and only 3 games if your search position with Qa4-Nge7, but White lost one tempo (Bf4-Bd2 ; Bg5-Bd2) in first and second  game and exchange queen in the third

doesnt in line a) 7 qg4 ne7!? also transpose to a poisoned pawn mainline or  are there tricks with moveorder that doesnt make it playable? Maybe white then can play an improved version of the geller variation