I briefly owned a Prizm IV, and in the future might get a used Prizm V to use as a loaner.
I hunt a lot of sites, and more often than not they are quite mineralized as well as littered with small iron trash (nails and such). This presents a few challenges, such as it creates some difficulty to try and pinpoint in a threshold-based All Metal mode. Since it is often necessary to pinpoint with slow, short-stroke sweeps in the Discriminate mode, I prefer to use a model that has a quick response and recovery. The Prizm's don't. Simple fact. So I favor my IDX Pro or other Classic models for their pinpointing ability in the Disc. mode.
Also, because I hunt in some "bad ground" environments, I prefer the Classic series due to the easy acces to a more durable trimmer so that I can set a Ground Balance that will let me use them anywhere, and the GB trimmer is tied to BOTH the All Metal and Discriminate modes.
Many of the sites I hunt have a good deal of brush. The overgrown fringe areas of larger parks, wooded sites of long-ago mining, logging or other activities, or the sagebrush-covered desert ghost towns, to name a few. I don't like having a headphone cable dangling or in my way, or getting hung up. I prefer my high-end quality Killer B 'Wasps' and their stout, short coiled cord. I also prefer the fact that they plug in under the armcup of my XLT, MXT, IDX Pro, or other White's models. I detest the odd-duck location of the headphone jack on the Prizm series. Personal preference.
Also, due to the fact that I can get 8-AA alkaline batteries for $1.80, and due to the long life I get with them for the cost, I prefer to use models that are powered by Double-A's rather than 9-V batteries.
Most important, perhaps (other than the quick response and recovey of the Classic series) is the fact that I hunt sites that tend to be trashy, brushy, or have building rubble. I like to hunt close to metal fences and structures. In open, grassy areas, a decent 8" or 950 is fine, but I do at least 95% of all my detecting with searchcoils that are 5"-6
