I have the Arca-Swiss D4 with classic screw clamp which I use with my Linhof Techno. My original intention was to replace it with a RRS flip-lock clamp, so I bought the classic because it was the cheapest (you couldn't buy without clamp) but that was before I knew Arca had replaced their loctite with a new one which is near impossible to remove. It's probably possible to remove if you got professional heating equipment and skill but it's not as easy as it was before.
Of course disappointed that Arca had removed the possibility of user customization, but anyhow I ended up getting used to the classic clamp. I had a screw clamp on my previous head too, and actually I don't really see much use of a quick lock for this type of camera. It takes about 3 seconds to tighten, and seen to the workflow as a whole reducing that's not bad. The thing is that you don't loosen the clamp more than you need to remove the camera (you tilt it to the side the same time as you unscrew so it pops out just when open wide enough), and then it takes very few turns to tighten it again. Quick lock will probably save you only 1 or 2 seconds, if even that.
The strong points of the screw clamp is that you get more pressure than flip locks, and that it's not sensitive on the exact plate size so you can use third-party plates without issues. It's also more easily operated with gloves which is a plus for me that shoot in cold weather during winter.
If I would buy again I would get the classic clamp again. None of Arca's clamps have the same good look and feel of the competitors like RRS. Arcas are smaller and look a bit cluttered, but anyway it's not much one can do as these are more or less permanently fastened these days. And then I prefer the classic clamp. If I could get one of those huge flip lock clamps like RRS I might have got that one instead, but I kind of like the screw clamp.
The D4 head itself is great and works nicely with the Techno, despite the Techno is one of the heavier tech cams out there (at least when the sliding back is attached). If used to locked gear heads one have to get used to the unlocking knobs which can feel bit insecure, I actually did a classic finger squeeze the first day with the D4 (ouch!). Not used to ball heads or anything like that I thought those locking knobs would sit securely if just casually tightened, but of course one needs to tighten them hard. Learning the hard way I know always tighten them hard and have never had problem since. Actually it's quite nice to be able to unlock when working with vertical positions or other extreme angles which I sometimes do. When working in extreme angles the pano needs to be tightened hard too as otherwise the camera may turn.
About losing the system off the head with a screw clamp, I have no worries. You should make sure that your plate has pegs just as the clamp so that it cannot slide off when loosened, that's an important feature. What then happens if you have your head tilted and you by confusion loosen the clamp instead of say the pano it will slide and stop against the pegs, or more likely it will stop earlier due to the camera tilts and creates friction. I have actually tried this. One disadvantage of the screw clamp is that you have screwing motion both on the clamp and on the top pano, to very different screw motions though but still my brain sent my hand to the wrong knob when I had my eyes on the ground glass of my tilted camera and then I unscrewed the clamp instead of the pano. I became a bit surprised when the camera slided a few centimeters, but there was no risk of falling off due to the pegs. It had stopped due to friction before the safety pegs was used though.
With the Techno I use a really long plate with two screw fastenings, I recommend that.