I currently own both an Xterra 705 gold pack and an Etrac. While I'm fairly new to Etrac, I put in 5 years with the Xterra. I am finding that the depth is much better with the Etrac, average finds depth for my Xterra was 5-6" while I'm now im consistantly finding targets now at 10" with Etrac. Head to head, you'll do well with the Xterra and do so for half the investment. But if your budget will allow the extra cost of the Etrac, I highly recommend it.
Keep in mind that Etrac doesn't come without its minor issues, the visibility of the display is terrible. At the end of the day you'll hunt mostly by sound anyway and you'll find that you can deal with the display glare. Etrac batteries are rechargeable and you need to recharge every outing, they take 12-15 hours to do so. Xterra batteries get changed about twice per year and take 4 AAs. Etrac is heavier than Xterra, the first couple of outings you'll really notice the extra weight, but you'll get used to it. Etrac is transmitting multiple frequencies at once, you have to swap coils on the Xterra and the coils are $150+ each. Take that into consideration and the Etrac cost starts to come more in line. Think of it this way, an Etrac is an Xterra on steroids using more than one coil at a time.
The Xterra guys will say they're as good as an Etrac, and on average that's true, but who wants to be just average and miss some of the good/ deep stuff. I'm and Xterra guy too so I'm not knocking it, IMO it all comes down to what the budget will allow.