TFSA doesn't shelter you from American taxes is my understanding... I'll have to look into it..
" if Canadian residents purchase US-based securities (such as Microsoft) in a TFSA, a 15% withholding tax applies. Thewithholding tax has nothing to do with the Canada Revenue Agency. It is charged by US tax authorities on US investments held by foreigners, including Canadian residents. "
Not sure that would apply...
http://www.canadiancapitalist.com/withholding-tax-tfsa-investments/