Honestly, here's the thing:
Lee Sin and Jarvan and Vi are stupidly strong in the jungle, as they always have been and always will be because Riot is perfectly content to completely ignore the fundamental problems in their design (and the stranglehold they have on jungle viability, particularly in Lee Sin's case) because they're flashy. For some reason, looking flashy and having fans completely excuses you from real balance changes and reworks.
however, if you look beyond the "OP jungle trio" as you might call them, the next issue you encounter is people saying "omigod jungle is way too hard now". This is something I pretty much disagree with. I think the only reason people think the jungle is "harder" now (speaking as a jungle main who's played League since it's release) is because they're either forgetful, or spoiled by the jungle of the last couple seasons.
Making the jungle as hard as it is now is something many of us jungle "veterans" actually begged Riot to do last season. This is because, back in Season 1, and Season 2 (to a lesser extent) the jungle was super hard. If you think people struggle now, imagine a jungle where literally the only viable (as in "only ones who can even remotely clear a route let alone gank) junglers were like Master Yi, Warwick, Xin Zhao and Nunu. Season 1 jungle OP yo.
Over time in the interest of opening up jungle viability, Riot made the jungle easier and easier (with Lee Sin being a dominating pick shutting out most champions from the jungle and Riot acting all confused), culminating in what we had with the "spirit stone era" of jungling, where you could jungle a damned Urgot and be effective. Riot then created an almost whiplash-like effect with their most recent rework of the jungle, such that the only junglers who maintained the same effectiveness (almost) were, (big surprise) the "OP jungle trio".
The result is this recent wave of "wahhhhh jungle 3hard5me", and the fact that Lee/Vi/J4's ridiculous amount of power is incredibly apparent now, as it's hard to get more obvious that you're too powerful than "hey, everyone but these 3 champions is struggling super hard while they barely break a sweat". I'm not saying the jungle doesn't have a horribly unfavorable risk/reward ratio for junglers right now (unless you're one of those 3), I'm just saying it sucks for all the junglers just about equally so it doesn't really matter for any of them (again, unless you're one of those 3).
Now, the entire point of that whole shebang of a story was to say that Quinn's kit is about as ideal for a "jungle ADC" as you're ever going to get. It's just damned near everything you'd want. As such, I'm a firm believer that the jungle should be Quinn's "main" role. Regardless of whether the preseason helped her out in the jungle or not, the fact is unless you're playing one of the "OP jungle trio" champions, your effectiveness is basically irrelevant, as by comparison to those 3, all the junglers kinda suck. Doesn't really matter if you're in 27th or 42nd place in a 2minute dash if there's 50 places and only the top 3 get rewarded or have discrepancies in finish-times bigger than a few seconds, does it?
The TL:DR is if you wanna do Quinn jungle, I say it's easily her best spot and every jungler who isn't Lee/Vi/J4 is having a shitty time in the jungle anyway, so why not play her in the jungle?