I would say stick with your HDS and wait for the newer versions of the Novatac to be released. That would allow for them to improve on things...
Ditto that. I also have a Milkyspit-modified HDS U60, and it's an amazing light -- at least 120 lumens, beautiful beam pattern, retains all the usual HDS features.
However -- if you didn't already have a modified U60, the choice would be more difficult.
If you had no HDS light at all and want a light of that type in the near future I'd suggest The Novatac 120P.
If you had an unmodified HDS, it would still be cheaper to have Milkyspit modify it than get a new Novatac 120. Or you could sell the stock HDS and then buy the Novatac 120.
But you already have (essentially) an HDS U120, so I'd suggest holding on to that and waiting to see the new HDS lights.
If you wanted something a little different in the same quality and form factor range, there's the new Arc "PD".
With my U60 boosted to over 120 lumens, I rarely take my U2 or Fenix, Fire~FlyIII or Fenix L2D CE. The U60 goes brighter, dimmer, is smaller than all but the FF3, has adequate run time, and runs on both primary and rechargeable cells.