Your questions do not seem to make sense. Not sure if it is another Nikon vs Canon brand war baiting troll post.
• You are asking should you go for FF. You can have FF with Canon or Nikon or Sony or (Pentax K3?)
• You asked is it worth switching to Nikon. Brand change has nothing to do with going FF. What has "worth" got to do with it?
$2K budget to get FF DSLR plus 70-300mm L IS & 100mm F2.8 L Macro lenses? Good try. I would like to have a Roll Royce for $50. (but even if someone willing to sell at that price, I cannot afford the COE and road tax)