XPRT/WD vs. RATL-R Comparison
Having been tweaking on FRT for the platform since before there were commercial options available, I figured trying both of the ones you can buy off the shelf currently would be a fun back to back comparison.
I'm putting the XPRT and WD in the same basket as they are functionally identical, with the primary differences being the XPRT bundle has CNC aluminum hammer, lever, and forward sear, where my particular WD setup ran a CNC Delrin/POMH hammer and the stock sear, with both printed and metal levers.
I had been running the XPRT/WD setup since the file was first posted by $RANDOM_BANNED_OP, as I was already set up with a first-gen hammer and three position aluminum selector from working on my own FRT before commercial options were available. I decided to pick up a RATL-R just to make a direct comparison, and because I have multiple PS90's.
Some notes about the XPRT/WD:
Not the most efficient means of harvesting the energy available in the cycle due to multiple stages of high friction elements
Easy to bind the bolt by pulling too hard on the trigger, can be eased with overtravel limiters
Achieves the trigger reset on the back-stroke as part of the hammer reset action
More true to the original design intent in its simplicity (IMO)
Some notes about the RATL-R:
Gets its energy directly from the bolt on the return stroke
Less potential for bolt binding, but pulling too hard will still interrupt the cycle
Works with any three-position selector, not just the printed one it ships with
More involved disassembly/cleaning routine due to having to take the RATL-R sled out before you can remove the bolt
The quick version is that both of them work, get one, get both, you'll have a good time.
The ungineer tweaker in me doesn't think either solution is ideal.
The XPRT includes some unnecessarily blingy parts in the form of the CNC'd hammer/forward sear. I prefer to keep the trigger pack as close to original as possible, so using the original sear with a Delrin hammer was preferred. The moment you make one part in any mechanical system stronger/harder, the next weakest part in line is going to be the one to fail or wear prematurely. I believe this is why they went to the extent of including the forward sear in metal. There is more friction in the trigger pack, and you can feel it during the reset.
The RATL-R sled seems a bit fragile to me, only time will tell what sort of longevity it can attain. There is more friction in the RATL-R system on the trigger pull side of things due to the large surface area of the sled and that it kinda forces the trigger bar rods outward a bit, and you can feel it during the trigger pull. That being said, the overall feel of the RATL-R during operation is a bit more operator friendly than the XPRT/WD. You don't have to be quite as mindful of what your trigger finger is doing. It is however more of a task to break down and clean, which does bother me a bit.
Rounding the edge of the hammer to free up the reset as described in the RATL-R install video can benefit both systems. Getting full mag-dumps on either of them is more of a challenge than it would be FA, but that's the price we pay to stay legal.
Both of them are a good time, both of them do the job roughly equally, both of them will send dollars downrange in fantastic ways.
This is just my $0.02, I am not in any way affiliated with either company and gain nothing no matter which one you choose. We all benefit from you choosing one though, because in-common-use will help them remain above board, so get out there and BRRT it up Stargate style.