So I thought I'd post my further experience in regards to the 3S vs. PD lights. It seems since I re-acquired an LS20 that I have re-trodden the exact same ground that I covered back when I first got my Haiku!
At first, as I posted, I was really really happy to have an LS20 again, and I EDC'd it for a number of weeks and admired and played with it regularly. But then, gradually, over time, I just stopped using it that much and mostly used my Haiku because, well, for all the reasons that I talk about in the first post of this thread!
I understand--I really really do--why people love the PD lights, and I felt strongly enough about it that I spent a lot of money to own one again. But, once again, I'm back in the same position of rarely using my LS20. My Haiku is my workhorse light. It is awesome, practical, convenient, and the High CRI LED in mine throws such a beautiful light. Nostalgia and regret and love of the Piston-Drive concept are what prompted me to buy an LS20 again, but it is still my considered opinion that the new lights have surpassed the PD lights. Just my personal opinion. YMMV!