not much difference
2 cutoff is 2 cutoff...both poor. The 6/8 Deck game has a SCORE of $23.41 for playall 16-1 spread, the 4/6 game has a SCORE of $24.78.
Add wonging to the mix and the SCORE 6/8 16-1 game is $36.38 and the 4/6 game is $37.62 (wonging out at -1 True using Halves count & all index numbers)...N0 for both games is around 27,000 rounds.