I would say that overall, the Discovery is going to be a bit better.
That being said, the Tracker IV is a great little machine for what it is. I've found all kinds of great stuff with mine (silver coins, gold and silver jewelry, IH pennies, TONS of clad, etc.) and it's responsible for getting me back into the hobby.
The thing with the BH machines is, you're not going to get the depth you'll get with higher end units. On average you can count on 6-7" for coins and jewelry. They'll detect trash like soda cans much deeper but who wants to dig soda cans??
I've never used the discovery 1100 personally but from what I've read it's pretty good for what it is. It definitely has a few more bells and whistles than the T4 such as depth indication (which is PROBABLE anyway).
Either way you'll definitely find stuff with either. It's up to the dedication you put into the hobby and choice of locations.
If it were me and I had to choose between those two, I would choose the Discovery 1100 but I also wouldn't underestimate the Tracker IV at all. I believe the T4 is one of the most under rated machines out there. It's simple and basic but it does find the goods down to a limited depth.
Good luck and HH with whichever you choose.