MEV, what kind of hunting do you plan on doing? It does make a difference as not all detectors have the same strengths.
The FBS machines are great for coins, especially silver and other high conductors. Due to the low op freq they handle ground minerals and iron very well. The FBS machines also have accurate TID to greater depth than most VLF machines due to the unique way the received data is measured and processed. The TID is superior to most VLF displays due to the Fe-Co grid that provides far more intelligent information than the typical phase angle display used in other detectors. The CTX is better balanced, though heavier, than the E-Trac but has less felt weight due to the distribution of weight being further toward the end, which helps balance the detector. Thus, it is less tiring on the arm to use.
The drawback - the FBS machines do not register most small jewelry or thin rings. Again, this is due to the very low op freq - so if you are a beach hunter you might want to look elsewhere. The CTX is superior to the E-Trac at separating non-ferrous targets in a field of ferrous (iron) and will get a bit more depth (1/2 - 1") over the E-Trac. That is, where the E-Trac will null the CTX will still produce audio and TID - at least to a higher degree than the E-Trac.
As for depth, the FBS machines are in the top bracket. There are other machines that also go deep but they usually can't provide accurate ID beyond 5-6", so the FBS machines have the edge.
In my opinion, the CTX and E-Trac are extremely simple to operate. The settings are simple and rarely need changing once set. You get your various custom patterns and audio bins set (about 45 mins work) and you're all set for just about any kind of hunting. I fail to understand why people complain about how difficult it is - it is about fully automatic and the menu structure is intuitive. Compared to some White's models where every last thing is adjustable and you never can be sure if you've got the best setting the FBS machines are child's play.
I would look for a used CTX - they are out there at a good price. If you buy new the price is steep compared to some other great machines that are half the cost. So, you have to decide if you need the extra depth and the better TID. Many people do just fine with the AT-Gold/Pro, Omega, or some Tesoro models. It isn't like other machines pale drastically in comparison. Honestly, the difference in machine technology isn't that great and most reputable manufactures produce machines that are more than capable for coin hunting. With these you may miss a few deeper coins if it is displayed as ferrous when it was non-ferrous, and you pass it by. Or you may get a few more gold rings because the VLF machines hit hard on them whereas the FBS is weak.
In the end, you are not married to the machine. If you try it for 6 months and put over 100 hours into it, yet you aren't satisfied - sell it. You probably aren't going to lose much - especially if you bought used to start with. You really can't go wrong. If the FBS isn't your thing then sell and buy something else. Once you start comparing machines and see how close the field really is you wonder why you were fretting at all.