I should, of course, note here that what is being discussed is the best way to fight against the SNP. I think, as already stated, that going down the lie route a difficult one, and given the current court case with Alistair Carmicheal's admitted lie, certainly not one for the Lib Dems.
This is neither saying that no one in the SNP has lied nor that there is not stuff they can be attacked on, just that the attack is better focussed on areas where the Scottish Govt can be argued as failing such as education, policing, and slightly less clearly the NHS.