G'day Cory.
I haven't used the Lone Star myself, but the first detector that I did use, was the Bounty Hunter Tracker 4. On the up side for the Lone Star, you have automatic ground balance, but that's about it.
The Ace has 12 notches of discrimination as opposed to 5 on the Lone Star, The Ace has 2 pinpoint functions, which once you learn how to use them, are very accurate. On the pinpoint feature alone on the Ace, is the best one I've had out of the five different detectors that I have owned. I became that frustrated with my tracker 4 in not being able to locate my target after having passed over it, that I nearly gave the hobby away.
You will find that you will get better depth on the Ace over the Bounty Hunters as well. If you hunt on sand, then that will become important. The large coil is also got a couple of inches on the large one for the Bounty hunter; it is also elliptical in shape, which will give you a much better coverage of real estate.
Out of the five detectors that I've owned, which include the Tracker 4, a Sovereign, an X-Terra 30 (which I still own and enjoy) The Ace 250, and a recent purchase of an XS Explorer (which I don't have a huge amount of time on) my favourite, is the Ace. It has given me the best overall satisfaction. I use the other 2 that I own, but I generally grab the Ace first. Mainly because it's light, reliable, gives you a fair idea what the target is, and has a deadly accurate pinpoint, which I consider, to be second to none (I have played around with a Tesoro, which are supposed to be the best pin pointers, but from what I saw, it's no better than the Ace). Not bad for a cheap detector. It's not that I'm brand loyal, it's just that the Ace does live up to it's hype. About the only thing that I'm not to fussed on, is the bell tone.
Mick Evans.