Hmmmm, When I started on my cycle of moving to better glass I made (which was sometime ago) a decision that in the mid term I would go FF so only buy FF type lens ie 24-105 L. I made the decision about 2 yrs or so ago and though I still dont have my 5D :-( , I am glad I did as my purchase of the 5D3 is not that far away and considering the cost of he body I am glad I decided to go FF lens only and will not be burdened with the cost of upgrading EFS lens. Not sure what the Tammy is but just room for thought.
Well that is also my thoughts on lenses. As the 5D111 seems to have dropped under $3500 now, it's not far off for me.
Canon 6D
Canon 40D
16-35 L 2.8 11 USM
24-105 L IS USM
70-200 2.8 L IS USM 11