So what im wondering is ; Is it worth buying a Dorans blade as a first item, then getting another one + boots at first back?
Seen a couple of Dia/Challenger Lee sins always buying dorans when going jungle instead of machete + Hp pots.
It makes your ganks/counter jungle really scary, but makes you farm a bit slower and if you get really low for whatever reason you have to base since you have no pots.
I do prefer the dorans blade start, as it lets you kill pretty much any other jungler at their red with the exception of udyr. It's a perfectly viable strat and from my understanding is quite popular in the korean meta.
As others have said, it is mostly a tool used for situations where you plan to gank, a lot, like a ton. You can do it on a few others too, but lee is probabally the best for this plan.