Site specific

I must admit there have been a few times this year when my choice of metal detector has let me down at certain unexpected good sites, but when you use one metal detector the majority of your metal detecting time you will struggle away from where your metal detector usually shines.
Using one type of metal detector you really feel comfortable using makes sense, especially if the metal detector you use is perfect for detecting the main thing you normally search for. 
For me that main thing in south Florida is modern gold jewelry at tourist beaches, unfortunately tourist beaches happen to be very trashy sites littered with all types of undesirable junk.
To find gold jewelry at tourist type beaches you often have to go thru a lot of trash, including clad coins, fish hooks, bottle caps, tin cans and pull tabs, just a few things a VDI screen on a metal detector will help you identify.
Read outs on a metal detector screen such as target cursors, ferrous & conductive numbers, target depth etc come with a price, the trade off is target identification and target separation over target depth.
The alternative for me is searching in an all metals search mode digging everything or using a pulse induction metal detector, still digging everything only digging it deeper.
In my opinion no metal detector is good in every situation so it makes treasure hunting sense to use a metal detector most suited to detecting what you are searching for in the places YOU search. 
You may struggle away from your comfort zone, but you can adapt when you know what your favorite metal detector is capable of doing and sometimes just as importantly what your metal detector is not capable of doing.
Knowing you have to adapt to a different metal detecting situation shows you understand what it takes to detect what ever it is you are searching for under difficult circumstances. 
Perhaps even a change of search mode or search coil is just what the doctor ordered to help you detect something good if you are struggling in a difficult to search area.
The more I travel to different areas to metal detect the more I value and rely on different size search coils to help me find stuff at problematic sites.
In this already busy year of traveling to metal detect I also know it pays not to test or try new equipment on the road, sticking to familiar metal detecting equipment helps to get the job done. 
A busy year of traveling to metal detect has reenforced how important it is to play the averages away from home, rejecting a bare minimum of trash using average size search coils.
So much about metal detectors and search coils is site specific, something to think about if you search a wide variety of sites.