The Fisher 12XX series are good relic detectors, but they are single frequency, not dual. Some have dual discrimination, similar to the Tejon.
I would say trying to get the Tejon is a good idea. Manual ground balancing is easy once you get the hang of it. For the Tejon, once you have your pitch set the way you like it, your sensitivity set fairly high ( 7-8...don't run it too high to start off...you will still go plenty deep) just pull back the trigger and hold it in that position to put it into fast all metal and make sure you hear the threshold. If you can't, you have turn the threshold knob until you can just hear the hum/noise/whatever you want to call it ! Start to bob the coil up and down between 2 - 10 inches off the ground ( continuing to hold trigger back) and start to adjust the ground balance knob clockwise or counter-clock wise until the threshold sound while bobbing remains the same...that is, the threshold sound does not get louder when the coil goes up OR down. You want the threshold sound to be constant while bobbing the coil. Once the sound is constant, release the trigger and you are ground balanced. You can now either hunt in all metal or discrimination mode. I like using the trigger method of ground balancing as opposed to putting the unit in all metal because it has a faster re-tune when you pull the trigger back. As you are hunting and the Tejon starts to act squirrley or erratic, just pull back the trigger and re-check the ground balance. You may be in different soil conditions than before, and all it takes is a few bobs of the coil with the trigger pulled back, adjust the ground balance knob clockwise or counter-clock wise until you get a stable threshold, and be on your way. Simple. Just make sure you don't bob the coil too fast. A nice, easy up and down motion...just make sure the coil is parallel to the ground when you do it. Also, if you adjust the sensitivity up or down, make sure you re-ground balance. Some say you don't have to on most occasions, but since it's so easy to GB, I say do it.
Just think of ground balancing as a way to 'discriminate' out the ground minerals. You don't want the detector to react to the ground while sweeping.
The Tejon, being very sensitive, high gain, and using a high frequency, it can't get near the wet salt sand without seriously reducing the sensitiviy and upping the discrimination. Since salt water is conducitve, it 'sees' the wet, salt sand as one big target. I tried with both the stock and small concentric coil and the machine is too sensitive. On the dry sand, works like a charm and it WILL find small foil and gold. Similar...it will find deep bullets and relics AND coins.
The ONLY reason I sold mine is that I hunt salt water beaches 85% of the time and needed money for another water proof unit.