Sean,
I just took look at the line weight data for the XLT and found the 7/8 XLT weighs 876 grains. Since this is very close to the 900 grains of the 7/8 GS, which I really like on the T&T 1409, the 7/8 XLT should be dynamite on it.
The 8/9 XLT weighs in at 988 Grains, which is a bit more and would slow down the rod a bit; although it would not be badly overloaded like with the 8/9 GS and its 1100 grains.
Based on the weights of the lines, you couldn't go wrong with the 7/8 XLT on your 1409 T&T.