Regarding; Normally Working TRX
A person needs the "beep" to indicate ON/OFF. So, when the "vibrate only" mode is selected, you hear one beep when turned on, and one beep when turned off. However, during use, no beep, only vibrate to indicate a metal target.
Some misunderstand, display back lights, vibrate modes, headlights, are designed for searching after dark, for not having to remove your headphones, or for those with hearing difficulties... that's it. No reputable (in it for the long term) manufacture will ever intentionally offer features specific for stealth hunting as that can be construed as facilitating night hawking.
A metal detector designer / manufacture construed as intentionally / actively facilitating night hawking would be horrible (long term) for the industry and hobby. Law makers already dismiss metal detector manufacturer's efforts to keep areas open to metal detecting as strictly 'for profit" efforts... I have testified about it in court and heard it first hand, "manufactures only want laws favorable to metal detecting so they can sell more metal detectors". If they can construe a manufacture as supporting or promoting night hawking, it places the entire industry / hobby / profession in a unfavorable light, as well as gives credibility / justification to laws prohibiting metal detecting from many areas. Night hawking is really bad for the metal detecting industry as a whole, and especially bad for the manufactures.
If one is looking for truly stealth searching a person will certainly have to modify their equipment. Manufactures can not allow the perception they support stealth searching as it plays into the hands (provides significant reasoning) of some law makers who want to outlaw metal detecting.
Howard