Well I started with my DCTs 7 days ago and the two I have been running have both been rock solid, I am still impressed by them and given all of my bitching about the CE4s and other inconsistent products, I figured credit where credit is due! So thank you TW, you've really done the business for me with this product!
My only complaint is that they should come with a ming style drip tip to avoid the tanks riding up the carto but we've discussed that elsewhere (and hasnt really been a massive issue anyway if I am honest) and hopefully TW will stock these at some point in the future. I have had absolutely no leakage and I leave these things horizontal on my desk and likewise in my car rolling around the dashboard, nethier have I had a drop of liquid in my mouth which was always a possibility with the CE3s on occation.
My 3.5ml has seen most of the action, having easily vaped 30mls + of absinthe, I noted it was a little hard do draw on today and vapour production was down, no complaints but I thought I would start a fresh one and boil up the old one.
Boiled for 20 minutes and dried out on a hot radiator. Reading 2.8ohms on the meter so decided it was a lost cause and thought I would pop it apart and take a look at the state of the internals and also to see where the 2nd coil sits.

As you can see, there has been a little burning going on in there, you can see in the outer wadding where it has also burnt a little but it has been hard used, a lot of full length vapes on the ego battery (what is that, like a 10 second vape?) and a lot of chain vaping. unfortunately in the excitement of taking it all apart I don't recall which bit of wrapping came from which coil. The second coil seems to sit approximately half way up the carto for thse who are interested and I suspect that the majority of the burning was from this coil as I feel it probably doesnt see as much liquid as the bottom coil. Thats just a complete guess however so when I pop the carto from the 6ml tank apart I will pay more attention.
I popped it on a tornado battery (probably should have used the ego batt in case I'd shorted anything but oh well) and fired it up, both coils started to glow really well so it possibly would have seen a few more ml before being totally useless but there's no way with my fat fingers that I could have put it all back together.
Anyway, whilst it was all apart on my desk I had a little bit of a brainwave.... As I've mentioned before in other posts, I have a large stock of 510 XL DC Cartos that I bought for next to nothing back in Decembers yoyo. I've spent a long time peeling the black sticker off a couple and removing all of the glue so it would fit inside the DCT tank, this wasnt the quickest, most enjoyable job in the world but I was happy that they were ready to be punched so I could use them in the DCT. Sat looking at all of these bits on my desk I figured that I already had a punched outer cylinder from the DCT carto I just ripped apart... I carefully removed the outer cylinder from one of those prepared DC Cartos (they definitely don't come apart as easily as the DCT carto) and replaced it with the one from the DCT carto, hooray!
Providing the outer metal cylinder has a good seal on the new DC base and doesnt leak, I don't need to bother peeling those pesky stickers off the 40 or so DC cartos I have! Admittedly I havent used it yet and it might be a few days before I get to it but in theory there's no reason why I should have any problems. I don't have my NIST certified multimeter here with me but I do have a cheap and nasty one sat on my desk, it may not be totally accurate but the DC carto with its new outer metered out at 1.8ohms so it doesnt look like I've damaged anything in the changeover.
All being well I have enough cartos to last out most of this year, happy happy days

Hopefully swapping the metal carto cylinder is a handy tip for any other 510 XL DC Carto users out there who may have invested in a DCT whilst also having a stockpile of the old DC cartos.