It's all about the right tool for the job, and sometimes that will be a PI, other times it will be a VLF. Sometimes I need a sledgehammer, but most of the time I need a carpenters hammer…
In the gold fields I use a PI (Garrett ATX and before that a Minelab GP Extreme) for deep large nuggets, and a VLF (Gold Bug 2 or AT Gold) for the really small shallow stuff. I've searched ground so hot that it is difficult to use a VLF at all, and the depth is severely reduced, and in those areas the PI is king. If bedrock is close, then there isn't any need to swing a heavy PI, as long as the VLF will ground balance properly.
If I'm searching a beach I use my Garrett Sea Hunter MKII for the wet sand and in the surf, and I use my AT Pro in the dry sand. I want the depth and ability to handle salt water that the Sea Hunter provides and I can deal with digging junk, but in the dry stuff with the ability to knock out iron and accurately ID most (modern) pulltabs from rings, and audio that keeps me from digging bottle caps makes the AT Pro my choice in the towel line.
Weight is the downside of a PI, and the lack of discrimination. Hip-mounting or using a bungee support can help with the weight. The ability to ignore mineralization and gain a noticeable amount of depth is the upside. VLF machines have great trash separation and target ID abilities, excellent discrimination (I use very little however), and typically the machines are pretty lightweight. They also sip batteries, and PI detectors suck them dry quickly. Those are just some of the reasons why VLF detectors are still the top choice for most metal detecting applications. If they ever get a fully discriminating, accurate target ID, lightweight PI detector the VLF will go the way of the BFO.
Simply put, I use a PI where it is most effective, and a VLF where it is most effective. And I'm grateful to have the option.
