Tom:

1/   When I first used drills, there was no such thing as keyless chucks (at least to my knowledge). I was taught to run it up snug with the motor and then tighten the chuck with the key, REAL TIGHT. I've always done the same with keyless chucks.
Agree with this.  My ancient B&D hammer still doing its job – but, long since, have wacked chuck-key with hammer to be sure.  Now only used for the odd drilling into hard brick.

2/   By the way, the previous chucks hold fine if you give them that last securing twist by hand. You can't just run them up using the motor.
Well, watched your video – my old skin (between thumb & pointy) would soon get red raw; having to use that amount of ‘grip & twist.’
Also, would be more reassuring if bits were then used to drill lots of holes into (hard) wood.  Didn’t JMB do something like that in another thread?

3/   The new chuck does seem better...
As often pointed out in different threads, people can have different experiences with the same product.
But that doesn’t mean (and I’m sure it wasn’t meant) that others don’t have genuine, and valid, concerns.
How come?  Maybe production run tolerances, how someone uses a tool, etc.
In the context of this thread, your comment might be perceived as just (a tiny, itsy, bitsy amount) patronizing – particularly when considering others might be bubbling with frustration.

4/   I bought a C12 earlier this year, at what I considered a reasonable price.  Just checked – manufactured in 2008.  Has non-ratchet chuck.  Like yourself, thus far, no prob’s – like Alex, rarely used.  In one way makes it worst; because if used frequently, any potential ‘flaw’ would show up much more quickly.  Makes me wonder if they threw it in just to complete the set.
But!  Will I become dissatisfied in the future?  Wonder how I’d get on with the 3 year guarantee if I do?  (rhetorical questions.)

Please do not misunderstand the tone of some of above comments.   
Feel somewhat obliged to acknowledge the truly impressive support you, and others, give on this forum.  Thank you.


Alex.
+1 regarding customer support in USA.  Get the impression support here, at best, inconsistent.  Could I be been ‘green’ with envy?

Last comment – honest.
Bought DeWalt 18v package just over 6 years ago.  Flexible neck torch, circular saw + 2 blades, jig-saw + assorted blades, 115mm angle-grinder + 2 discs, right angled drill, reciprocating saw + some blades, twin battery charger, 4 batteries, the 2 different vacuum cleaners, a huge storage box, and, the XRP 3-speed hammer drill.  The lot came to just shy of £900 (just found receipt lol.)  The ratchet chuck has never let me down.  In fact, none it has let me down. I cannot speak highly enough of the kit – well batteries could be better – but times move on.
Now I don’t know, for e.g. what a T15 or whatever, cost back then – but do you know what?
For what Festool charges, I wouldn’t expect any hassle.
If anything turned out to have some sort of ‘short-coming’, I would expect it to be sorted – without any big discussion or cost to me.
Yes, for example, change JMBs’ chuck, and be pleased to do it – the cost to Festool isn’t what we pay!!
My expectations might be high, but so is the cost of Festool equipment.