Not going to get involved in a no chill vs chill debate, what you do in the privacy of your own brewery is your choice.
But, I will correct any misnomers that may skew the debate and there are a few here.
I am a chiller. I don't brew until my yeast is ready so there is no last minute panicking and pitching of 'whatever i have on hand'.
If this happens in any brewery it's poor planning and has nothing to do with chill or no chill.
The idea of using identical wort is somewhat of a misnomer. I can brew the same brew over and over again. The first time i wont have any identical wort on hand to have been able to build up a starter with prior but from then on i can freeze part of the batch and use it in a starter for the following batch. Zwickel does this regularly, I don't as i tend to reuse the same yeast for a number of batches and either top crop if the strain is suitable or reuse yeastcake.
It's nit picking to some degree but then the whole debate of chill vs no chill is.
I'm not really interested in a vs debate either as I hope I've made clear (by previously stating exactly that). I'm, like you, hoping to address some fallacies (not misnomers - you can be anal about science, I'll be anal about language) inherent in the OP and subsequent follow up.
I'm not suggesting that every chiller is frantically scrambling around trying to coincide their starter with their brewday. Of course you can hold off brewing, brew and freeze, etc etc. I'm merely pointing out the convenience of no chill from my perspective in that regard. I hardly ever brew the same thing twice too so, at least for me, no chill gives me the ability to ferment at will with starters made from the same wort. It's not the only way. For me to suggest it is would be to buy into the vs thing in which case I may as well stick a potato in my left nostril. I'm interested in neither (nose potatoes and versus debates) and I'm interested in both (Chilling and no-chilling).
Probably clear as mud but I can always try and clarify tomorrow if anyone cares.
Simply if I plan a starter and I plan a brewday and the starter doesn't work out so well, I have an extra option that I may not otherwise have. If I chilled all the time I could probably work it out but I don't currently need to.
@forkboy: I don't really. I just design recipes around a process that works for me. If I brew a beer that doesn't rely on loads of hops (single addition or simple bittering/flavouring/aroma additions), then I just do that - 60 min, 20 min and 0 min. 0 min is added at whirlpool which is usually 20 minutes after flameout. If it's a super hoppy beer, I usually burst the majority of hops from about 30 mins on with additions every 5 mins and then dry hop. I mentioned a side by side I tried using a plate chiller and a no chill (same wort, same brew, split). Definitely a difference - only an idiot would pretend there wasn't but as always it comes down to preference. Strangely, several other brewers, at different times, blind tasting and including at my brew club, picked the no chill as having better aroma. The NC was definitely more bitter but since the recipe was always NC, I found the chilled one a bit out of balance (has a lot of munich and crystal) so would change the malt bill to compensate if chilling. Hop flavour was definitely more distinct in the chilled version.
As for headspace in the cube: I fill to about 2 L short of the top, squeeze the air out when filling the cube as per the recommended NC method. When ready to pitch, I undo the cap to let the air back in, redo, shake to aerate then undo, add yeast, retighten the lid so it's just short of being tight. This is enough. Occasionally I get a tiny bit of krausen leaking out the top which is easily cleaned and sanitised. It just isn't a problem. I've filled cubes to the very top before and still had no major issues (some krausen leakage, clean and spray with starsan, move on). Krausen explosions happen with fermenters all the time. In a cube they seem slightly more restrained and just as easily dealt with.
@Bitter and twisted: I haven't entered loads of beer in comps but last year saw a 3rd place at worthogs pale mania, 2 x 1st places at Vicbrew (as well as a 4th and 8th and a 9th with ~30 entries per category) and a 4th and 11th at the nats with beers made no chilled, fermented with hop debris in the no chill cubes on top of the cold break and fermented with no fermenting fridge (water baths etc).
The Vicbrew 4th was a hoppy APA.
Yes I may have done better if I changed all that to chilled, no cold break, ferment fridge. Who knows?. I also beat many who chilled, transferred and used an STC1000 and generally, I think, did OK. I enjoyed drinking my own beers and some other people (brewers and non brewers, BJCP judges and non BJCP judges) did too. Good enough for me. Happy to suggest my beer is fine on that basis.
No chill works. It suits some people. Chilling works. It suits some people. If your beer is too bitter when chilling OR no chilling then change the hop additions in the recipe. Not hard.
Should add that I respect your experience having tried both methods and am simply relating mine. I am pro multiple techniques in all areas of brewing. HERMS, BIAB, NC, Plate, immersion - whatever. Different ways to make beer - that's what makes it exciting.
If I were to recommend a slightly more complicated/time consuming process that I find makes a difference (in my experience again) I would put step mashing, sepecially stepped sacch rests as being worthy of pursuit. Others may differ.