I did this on my build. Not only did it make no sense (to me) to have to dismantle the hub bearings to change the disc, the OEM setup also severely limits your options regarding disc choice. I used floating discs, for example, which would not have been possible with the OEM setup.
I did have problems with the TTT hubs however. Once everything was assembled, I noticed the disc had a visible wobble when mounted on the hub. I hooked up a dial indicator and measured something like .015" wobble at the outer edge of the disc. Obviously that was FAR more than could be ignored...most OEM manufacturers specify no more than .001" runout of the disc:
Then I measured the runout on the TTT hub without the disc attached, and got a .002" wobble on the hub face. I think that was the source of the problem, and the wobble just magnified on the disc face since it was much larger diameter. I measured my 45 year old OEM hubs, and they measured perfectly true, no wobble whatsoever. So after pondering things for a bit, I decided to just use the stock hubs. Since I have staggered front/rear wheel/tire sizing, I couldn't really see any downside to having 5 lug in the rear and 4 lug in front. This did involve getting new front brake hats machined, but fortunately at that time I had not yet ordered wheels. I mean, I would rather have used the TTT hubs, but I knew the wobble would have been a major problem, not just with the brakes but I am sure it would have introduced a "shimmy" into the steering wheel as well. Once I received the new brake hats, the discs ran perfectly true on the OEM hubs.
For the record, I do not blame TTT for the problem. I have no doubt the hubs were manufactured true. The way CNC parts are made, it would have been a far greater challenge to make them wobble than to machine them true. I think I created the problem when I pressed the bearing races into the hubs. Aluminum is very soft, and the bearing races are hardened steel. Unless they are pressed into the hubs PERFECTLY straight, I could easily see them distorting the bearing bore or shaving a small lip, in which case they would not seat perfectly true and could easily cause a wobble. I think that is what happened, and it is my fault, but I suppose it does raise some questions about the suitability of aluminum as a hub material.