I would NOT swap for XM-L or XM-L2 LEDs in the TK45:
- At those drive levels (sub 2A) luminous flux is about the same
- Fenix TK45 already is a floody light, but with a FABULOUS beam profile that is very useful and has a tad of throw for general/exploration/security use
I have the same flashlight and like it, and I too plan to upgrade it with either neutral white Cree XP-G2 or Nichia 219B. 
It will be challenging to find LEDs already mounted on 10mm round PCBs which TK45 uses (I already tried), so you either can ask this ebay seller to make some custom for you, or give a chance to reflowing LEDs onto original stars (or new stars, in which case I would upgrade with the nice copper sinkpads sold by the previously linked seller).
You can get both Nichia 219B and XP-G2 at intl-outdoor.