@afish there are older threads with lots of info on fittings, including alternate suppliers. Basically the quick coupler is the same as a European or high flow pneumatic coupler that is widely available. McMaster has quality fittings around $15 and cheap ones can be found in big box stores.

I'll update with links when I get time.

RMW

Not that Im aware of.  I know the majority are Tailonz.  But I have 100's of these things I have collected from various projects.  That crossed my mind too but more than likely the 6mm and 4mm I tested today were the same brand.  I noticed if the tube stays in the fitting for long time it gets slightly deformed on the end.  When I did the test this morning I did make a trim cut on the ends so that wasnt the issue.  I might have just had a bad 6mm fitting not sure. However, I did just eliminate as many as I could, based on past experience these fittings are not 100%

I too have also had good luck with the water variety but I still dont trust them but do have a few on my undersink filter.

I just got done pulling out the majority of the 3/8 soft line even though it wasnt leaking and replaced about 45' of it with 1/2" pvc since I needed a 3rd drop soon anyways.  I still have about 6' of 3/8 tube at each drop location and a ball valve.  So far no leaks and its been on for about an hour. 

Vacuum is harder to get a good seal on from my experience.  Plus there is a much smaller window for the pump to cycle.  Dont quote me but I think the pump comes on at 21hg and shuts off at 25hg.  It doesnt take much vacuum to loose that 4" of vacuum.  So not only is it harder to seal but its much more noticeable on pump cycling. I could probably go hours without kicking on the compressor with a small leak like that.  Unlike compressed air its also harder to hear any vacuum leak unless its real bad like in the 6mm test.  The test that lasted 10min. I could not hear any leak even with no ambient noise and putting them directly up to my ear.

If you are using them in compressed air scenario and have more than a few I would venture to guess at least one has a small leak.  With a vacuum pump that runs continuously you will also probably never notice a small leak but it could effect clamping force of the pod or bag   

Im thinking what Im going to do is mount the toggle switch valve on the bottom right side of my bench and plumb that over to the left side of my bench (since thats the corner where one of the drops is) with some left over 1/2 pvc.  That way when I need the clamp pods I can just take the one drop and plug it into the pvc (this will require one QA coupler) the output of the pneumatic valve will go directly to a 2 port manifold via a short 1/4 nipple and the manifold will have two 1/4 mini ball valves incase I want to use more than one pod at a time.  Or if I want one horizonal and one vertical.  I will try the 4mm push to connect fittings from the mini ball valves to the pod so I will only have two P-2-C fittings per pod.  If im only using one pod I can turn the ball valve off at the manifold.  crossing fingers the 4mm holds up and does as good as they did in the test this morning otherwise I will have to convert that to 1/4" tube and barbs.

I have a 4 gallon reserve tank plus whatever is in the lines but yes it is a combination of smaller volume and the narrow range of the pressure switch.  While 4 gallons isnt a lot compared to a 60 gallon compressor. I have noticed vacuum tends to get used up fast.  Even when bagging and I open the valve it only takes a couple seconds before the pump kicks on its almost instantly, and will take a few minutes to fully evacuate a 4x4 bag. Thats with a 4.3 cfm pump and 4 gallon tank. However, I have no desire to add a much bigger tank either, both for space reasons and run time.  While a bigger tank would help reduce cycles it would also just increase run time to refil the larger tank when it does cycle, so its a bit of conundrum. You have to replace every cubic foot of vacuum you use or leak one way or another, either a little at a time or all at once. 

My post was more to let others know to be mindful of leaks and the type and quantity of fittings if putting together their own vacuum clamping set up.  It doesnt take a big leak to make a big difference when working with vacuum even a very small leak makes a big difference and the fittings are the biggest offenders.  The braided line and barb fittings seems to be the bullet proof method which is probably why festool uses it. The smaller pneumatic line with push connect fittings can be hit or miss especially when used in a vacuum situation and extra diligence is needed. 

These small on board systems like the kronos with very small cfm pumps and no reserve would be especially susceptible to fitting leakage issues.  Im not sure of the vacuum pump specs on those small 12v pumps but it cant be much and they have no reserve tank so any leak will result in a pretty big reduction in clamping force. A singular one clamp setup isnt probably an issue but running multiple pods off that tiny pump gives me pause especially when there is push connects involved.  Im also wondering about those small bearing type seals.  When I was looking I couldn't find any that used a O-ring or rubber to make a seal.  They all looked like metal ball on metal seat for a seal.  I 100% would not be trusting that for a good leak free seal in a vacuum set up.  Im interested to know if the ones used in the Kronos system uses some type of rubber inside.  Vacuum and pneumatics is cool and fun addition to woodworking and offers tons of useful possibilities just be mindful before your project ends up falling on the floor or your foot. 

No unless you count a little spit  the only one that seemed like it would benifit from some lube would probably be the .25" tube in the 6mm fitting