@carnage0 really glad to hear you're digging Sinaloa! I still love that mix of ingredients.
Re: diketones, I've searched high and low for lab reports from 13th floor, even contacted them, but received no response about DA/AP levels in their juice line. The lack of transparency suggests there's DA/AP present, otherwise it's almost certain they'd be more open about it, as I'm sure they're aware of how people's concerns affect sales.
I originally intended to create something approaching Django without any DA/AP, and Sinaloa is the best I've come up with.
I'm personally not as bothered about that any more, though I understand people's concerns in this area.
I vaped a little more Django last night, and am now almost 100% certain there's RY4 present in the mix. (I distinctly recognise the somewhat sickly sweet twang at the back of my throat that I get from @Ckemist's Southern Smoke ry4 blend.) I think the RY4 is where the main Caramel note is coming from, but I'm also almost 100% certain the bitter, leafy tobacco top note is coming from a very different tobacco concentrate. It could be anything, tbh. I've not mixed anywhere near enough tobacco juices to be able to discern which particular concentrate is being used.
That said, I made a simplified 10ml sampler of my latest recipe, using Hangsen Flue cured last night, and even with only a quick hot water bath, it actually tasted a lot more similar to Django than any of my previous recipes.
My next tester will include ry4 and a small amount of Hangsen flue cured. I'm gonna try to let it steep for a few weeks and report back with results.
Re: butterscotch, I've personally found that butterscotch (natural) (FW) is a pretty complex concentrate. It develops some very interesting notes during steeping (almost subtle berry / fruit flavours after a few weeks), so it makes for some interesting recipes. I'm now no longer certain it's the actual butterscotch used in Django (I get slightly deeper, buttery notes when smell testing, which reminds me more of @NotCharlesManson's Royal Butterscotch, might suggest just standard Butterscotch (FW), but it's still worth buying the natural version, imo, due to its dynamic characteristics.
I've never actually tried dulce de leche, so I'm not much use in that area. Excited to see what you come up with down the non DA/AP route though!