If you are strrictly talking about "adjustability" or raw detection depth, then yes, the Explorer II is a better detector than the Quattro. However, for many that want a true "turn-on-and-go" detector with a much shorter learning curve that gives detection depth close to that of the Explorer, then the QUattro is not a lesser detector.
Again, why do you think Minelab came out with the Quattro? To convert existing satisifed Explorer users or reach the segment of the market that wanted FBS technology without the perceived difficulty of the Explorer?
Lesser is in the eye of the beholder . . . . . . I have had a few seasoned Explorer users tell me that they had bought a Quattro as a backup or for their child / spouse and then after trying it a bit, have relegated their Explorer to a backup role or for use in specific challenging sites. The ease-of-use and enhanced target id lock-on and pinpointing circuitry was better in their eyes.
My son - who has been hunting since he was 4 and can have any detector he wants (thanks to a dad that is too easy when it comes to detectors) - can set the Explorer and Quattro but would not use one in the field. His detectors of choice are the Minelab Musketeer Advantage (anyone seen his picture in the Minelab catalog?) and the Tesoro Tejon or Silver uMax with the Clean Sweep coil (for hunts). Are these "lesser" detectors than the Explorer? For him, most assuredly not . . . . . he finds things in areas others have long since given up on and for those that have met him at organized hunts, you know that he has competed in adult hunts since he was 10 and almost always places in the top 10 hunters. I know this is not a Bounty Hunter or Garrett forum but my daughter at 10 is extremely proficient with her Bounty Hunter 2200 and new Garrett Ace 250. Again, are they lesser detectors? For her, the Explorer is not even an option!
So, when you define "<span style="background-color:#ffff00;"><STRONG>LESSER</STRONG></span>", you need to determine what is important in a detector for YOU and what will enable you to be successful. If you are someone that wants to hunt but is either a technophobe or someone that simply wants to turn it on and dig targets, then the Explorer may be a lesser detector in your eyes. On the other hand, if you want to squeeze every last inch out of what today's detector technology can provide and are willing to put in the time to learn the detector, then you are right in saying "anything less than an Explorer II is a lesser detector".
Have a great day,
Andy Sabisch