Would the lower pressure and new LP tip allow you to put out less product, translating to less overspray and a more relaxed application rate?
For the occasional paint grade bookcase/cabinet/door, etc. would this be preferable to an HVLP?
That is the theory, that the product will be more controlled and the fan delivered at a lower pressure than with the previous generations. That is a good improvement. I have been using them since the very first ProShot in 2010 and have done everything from cabinets to exterior trims with the different models. You had to fly with them. Thats a lot of power to have in the palm of your hand.
Preferable to HVLP? That is going to vary from one person to the next. When the handhelds are good and working and maintained correctly, they are easier in some ways to use than HVLP. That is a two edged sword though. They have more power, so on finer tasks the handhelds can demand some technique adjustments from the user. For example, your distance to what you are spraying and your pace will be very different compared to HVLP. With some practice, it is pretty easy to sort out.
With both HVLP and handhelds, you can mess up projects, just in different ways - at different ends of the spectrum. Its a good comparison.
One place that the handheld might get the nod over HVLP among lots of users is in latex primer and paint. It can be difficult for occasional HVLP users to dial in for that.
For me personally, if I had one door to do or one bookcase or small set of shelves in latex, I would probably grab the handheld just because I know I could do it faster.
If it was a more formal piece in oil based clear, HVLP. As with most choices, it depends on the types of tasks and products you tend to be in the most.