This is my experience exactly!
My OG Mi (pre intake screen, pre turbulator) sold me on the RBT heater tech and I eventually added another unit to my collection.
Like your OG, mine needs no more than around 3 secs pre-heat, but the later unit needs a minimum of 8-10 seconds, and combustion is almost impossible (forget concentrates).
I returned my second unit to Ryan almost as soon as I got it, and he agreed to sort this (and faulty glass), (I explained that I'd like the new unit to be usable for concentrates, and as hot, or hotter than my OG).
It took 4 months, and a fair few friendly reminders to get it back (lol), and I can detect no difference to its state prior to returning it to RBT
, and #2 is most definitely a low temp vape.
In fairness, it delivers excellent low temp hits, and superb flavour, but the OG is a noticably better vape, and I can do concentrates with it, and I use it much more than the new one.
The 'heater lag' demands a loooong pre-heat, and makes judging the timing up to button release much trickier, even after the remedial work Ryan carried out.
The new unit has apparently been fitted with a turbulator, but it still suffers from hot-spots more than the OG, regardless of draw speed.
I also note almost no heat in the body of the OG during use, but the newer unit gets much hotter around the heater (not problematic at all, just an observation, it doesen't get 'burning' hot).
Overall the new Mi is somewhat dissappointing.
Sadly this experience put me off further RBT purchases.
I suspect that Ryan simply forgot to replace the heater when replacing my glass.
Returning it again for another looong wait (and I have to pay customs etc every time is crosses the pond) may just be throwing good money after bad (especially if he did indeed replace the heater, as I guess that I'd just get the same performance yet again).
Visually the new unit is beautiful, and I'm happy enough to keep it for low temp use, but the overall experience has put me off further purchases.
I never posted anything re' this situation before (I got the new Mi back months ago), as I feel Ryan has had some undeserved bad press, and I wanted to make sure I didn't contribute to that (the undeserved stuff) in any way.
But it has to be said that despite the fact that I wish Ryan the very best with RBT, I understand some of the customer frustration that I've witnessed here and elsewhere.
I have kept both my Millana's and will continue to use them though, as they are two of my favourite vapes even when compared to my admittedly indulgent collection.