I'll first state that I have not used any of the tipped TSX bullets yet, but I am curious about them too. They fix the lacking long range ballistics of the TSX bullet. Supposedly the tip on them is suppose to aid in even faster expansion. The hollow point cavity is larger I do believe with the tip filling it in. So as the tip hits, it pushes the larger hollowpoint cavity open and the expansion should begin sooner as a smaller amount of pressure should be required to start expansion. If you look back in recent bullet technology you will notice the Ballistic Tip bullets and Hornady even puts a tip on their bullets to aid in expansion sometimes. If your shots are under 100 yards, I don't think I would bother switching though unless you just really wanted to. I don't think you will notice much of a difference.
Federal is loading lighter weight Tipped TSX to fill a niche in the ammunition market no one else has filled yet. Hunting out west where people like flat shooting cartridges to shoot across the mountain ranges or even across the fields in southern states. They are generally deer hunting and don't require a massive sectional density to get the job done. So Federal is loading lighter than normal weight bullets to up the velocity and create a flatter trajectory. And like someone stated earlier, when a bullet retains essentially 100% of its weight, it kind of redefines sectional density vs penetration.
For example if you shoot a .270 130 grain bullet for deer with an average construction bullet and assume 80% weight retention (which even a lot of average bullets don't really retain) you will end up with a 104 grain bullet in the end which is less than the 110 grain Tipped TSX weight. Meanwhile the 110 grain bullet has a better trajectory.
It is all about where you want and what kind of performance you really want to get out of your ammo. For the last 80 years people have been harvesting animals with terribly constructed soft point bullets. We have come a long way and argue over small details it seems now a days.