@ Gambit
Great! -- hope you can post the games. (Bet you didn't favour 5 ...dxe6!
)
@linksspringer
Yes, 5 ...d6 is possible but Black's position looks pretty grotty -- I can't make sense of the N on g6.
I have the feeling that in the 4 ...e6/e5 5 de fe line, serious analytical scrutiny, incl. the use of strong engines, could throw up quite a few new ideas. White has numerous tries here, from the dubious(?) 6 e5 and 6 Qf3 through 6 g3, 6 Nc3, 6 Be3 and 6 Bd3 to the critical 6 Nf3 and 6 h4!?, and it seems there's little established theory on any of them! ChessPub forum, of course, is leading the way!
Footnote! In my original, no longer modifiable, post, I meant to write that it's after
6 Bd3, not 6 Nf3, that 6 ...d5 might or might not be strong ...