I had the SH II for 5 years....4 of them while in land-locked area of Michigan. There are advantages of the SH...
1) the control box comes with a holster to wear on your belt so the unit is very light weight
2) the PI technology is great for finding targets in highly mineralized soils without falsing.
3) the units often come with both coils, an 8" and a 10x14. In dense clay, the 8" averaged 9"-13" depth on a dime. The 10x14 was far deeper and could cover a lot of area and fast! I found my first silver earing back (maybe 1-2 grams?) at 6" with the large coil. At the beach, the large coil found some heavy iron targets, at knee deep.
4) they are waterproof. So if you drive 4 hours to hunt an old battlefield, you will never get "rained out"!!
Honestly, they are great for relic hunting and beaches that don't have a lot of trash. For the money, its hard to find another detector that will go as deep, and is waterproof.
Another thing is the speed at which you can swing the coil. The PI cuts through the !!!! and can be swung at a fairly fast speed while most detectors follow the saying, "slow and low." The PI isn't affected as much by poor swing technique either. Compare it to a minelab e-trac....you'll pry spend $800-1000 for a used one, then another 200 for a big coil similar to the SH2's 10x14. The result is the SH can be swung 2-3x faster, in the rain, and with the control box mounted on your waist; however, the e-trac does have the ability to discriminate unwanted targets and a fancy screen to display what it thinks the target will be.
So with all detectors, each has a pro and con. The pitfall to the PI unit is its poor ability to discriminate which means, you pretty much have to dig every signal and can't block out just iron, or aluminum, etc., but its pry the easiest machine to turn-on and start hunting....no fuss, no ground balancing, no settings...
For what its worth, I just sold mine for $475...included both coils with covers, the dive shaft, factory S-shaft and a straight shaft. Over the past 2 months, ones on ebay with both coils have been selling for $390-$500. Sold it because i don't get out that much and the beaches I hunt have an enormous amount of trash. So discrimination is a must if I want to make the best use of my limited time to hunt.
-David