I must admit I have reservations as to just how far £2.5B (if that is what the SNP plan to spend) will go in terms of defence funding. That said, the UK is fading fast on an international stage so what will we be left with as a UK soon anyway.
http://www.thesun.co.uk/sol/homepage/news/campaigns/our_boys/5005631/UK-falls-down-defence-spending-league-table.html
Someone else said it before, should independence happen, it will be because Cameron and co lost through a series of blunders. That and the fact that (Salmond aside) the SNP are doing a reasonable job of running things.