As an Englander I can't really comment but I personally think that Salmond, whilst being a smug, self-righteous twit is a highly competent leader of a separatist party. He is skilled enough to accept gradualist policies and he managed to fight the election on largely domestic demands for healthcare and eduction rather than on an overt independence platform (or at least that's the impression that I got in 2007).
With a more fundamentalist leader, I think that Labour would have just snuck ahead of the SNP and perhaps managed around 50 or so seats with the SNP around five or so behind.
I think that the election would still have been very close; remember the SNP only became the largest party by one seat; and Labour was not all that popular at the time. It could have all boiled down to a few people voting differently in one constituency.