P.S. A specific comment to the gent who mentioned that 'any serious racer knows you need knobs.' I honestly felt the same way for years. If you're covering a VERY wide temperature range in your racing environment then having an adjustable damper makes sense. But I don't think that's the case for anyone here. If it's below freezing you're likely not running a national championship. If it's 130F you're probably inside with air conditioning. I've worked with single-adjustables, designed my own double-adjustable reservoirs (with the help of ME's of course!), and incorporated technology from rally and F1. When you start to zero-in on the variables and make the reasonable assumption of a liveable temperature range for competition, the knobs becomes more of a psychological crutch than a required tuning aid.
I'm not being mean, just expressing my and many other people's experience. For those who may be familiar with Dennis Grant, he used data acquisition extensively back in the 90s while pursuing SCCA national championships. He found that adjustment was far less necessary than he had originally believed, once he'd made some good design choices (including Flat Ride, although he didn't specifically call it that). My own testing has shown similar conclusions.
I used to always rely on knobs to make setup changes, but looking back I realized that I hadn't optimized multiple other variables and I had NO IDEA what the dampers were really doing and if the change I was making was actually better in terms of lap times. I've found that the people who rely on knobs the most are using pitch-based setups where you NEED more damping to keep the oscillations under control. Using Flat Ride cancels those oscillations out so you focus on things like tire pressure temps that may be unique for a given track.
All the recent winning NASA and SCCA road racers I work with are using setups that have no damping adjustment. The bigger change they make is when it's very wet, they'll disconnect bars - I got that feedback from Anthony Z @ Edge after a Sonoma NASA race. This is why the springs + damping is such a CRUCIAL combination to get 'right' - because when you do, the vehicle works across a variety of track conditions, surface types, and temperatures (from above freezing to sizzling summer).
Yes, there may be a slight fall-off in damping, but a virtue of tuning for Flat Ride is you DON'T need as much damping compared to a pitch-based setup! You can really feel the tires working, and concentrate on your line, braking zones, etc., instead of going to the pits to tweak a knob. I did that dance for a long while and it was very frustrating and ultimately slower. You're not losing anything necessary when there isn't a knob - provided you're approaching suspension tuning from a thorough perspective. You're actually gaining a lot in terms of what I can make a damper (lower high speed compression slope) do when you use an 8mm shim stack vs. 12mm (drilled shaft) shim stack.
Quick summary of video - one damper (with 12mm post) had a high speed compression slope of 10.9 lb / in/sec, while another (with 8mm post) had 6.5 lb / in/sec. That's about 40 lb less high speed compression force every 10 in/sec of damper velocity. From a technical perspective, you end up with a wider high speed compression (and rebound) shim when you use an adjustable shaft, which leads to a higher high speed force and more potential for 'launching up' or 'jacking down.' It's much harder to create the kind of 'curb absorption' with an adjustable shafts.