I have been following this post and was reluctant to reply because I've replied to posts like this before. But you're asking for opinions so here's mine.
I have an Excalibur, Sovereign GT, two DFPI's and a MXT Pro for dirt digging. I love all the machines and they all have their place. I have found gold with all the machines.
However, I like the DF so much, and never wanted to be without one and I purchased another. The "Dual Field PI" has paid for ALL my machines and all my md'ing equipment, ( waders, wetsuits, gauntlets, scoops, floats, etc. ) many times over, and that is a fact.
Yes ,you have to learn it like all the other machines. I personally think some make to big a deal over the floating coil and that's OK I understand that . Also, pinpointing isn't a problem at all. When I see someone say, " it's a bear to pinpoint with" I feel they haven't figured it out. When you hit a target you pinpoint with the inner coil, not the entire coil.
I don't have an interest in any of the companies ( like some do ) and down the other detectors. They all have their place. I will say though, if you're only going to buy ONE detector, a PI isn't the way to go. You may want to save up ( and consider ) a new , or used Excalibur.... you can hunt in the water or wet/dry sand with no problem what so ever.
One last thing, and it's just my opinion. I'm not knocking the SS and you will find gold with it, but if anyone tells you the SS is going to out hunt some of the other machines out there with their advanced technology, I can assure you that it will not. IMHO