In short, Stout + QB:
Pros: Speed up your jungling drastically
Cons: Makes your early game jungling riskier and more restrictive

Without a question, QB will speed up your jungling time. Considering the 4-stack camp in Sent (4-stack instead of 5 since you’ll kill the top spawns way sooner than a possible 5 stack) and the 4-stack in Scourge, you’ll definitely hit level 4 sooner than a dual lane that’s taking no harassment. Experience wise, you’re faster than a dual lane hero, and a little slower than a solo lane.

Quelling Blade is more restrictive in terms of the camps that you can start fighting at level 1. Double stacking big camps (furbogs / centaurs / etc) is completely out of the question, and you’re relegated to the mid level camps in Sentinel / Scourge forest. Even in the mid level camps, if you get the wrong dual stacks, you CAN die without proper micro / tangoing. If your enemy ward your second half the 5-stack camp (the one with 3 stacks), then you’re pretty much F-ed. That leaves you little capability to tackle stacked high-level camps.

FINAL VERDICT:
Stout + QB might be better in scourge forest, since it is ‘safer’ from ward hating. In theory, this should bring you quick level 4s.
Double Stout might be still better in sentinel forest, given how often the bottom camp is warded. This built does not leave you handicapped to stack higher level camps.

First off, I don't understand why people are suggesting PMS (Poor Man Shield). PMS doesn't help you with creeps because the chance of blocking normal unit attack doesn't increase; it stays at 60% and 20 damage block but gives you the 100% 20 hero damage block. So don't go PMS unless you plan on ganking.

Now about the Stout shield + Queling blade + Healing salve (SQH). If you go SQH, then you will be forced to 5 stack first because if you double large camp spawn you will be killed. With the 5 stat camp and SQH you will finish the top 2 of the 5 stack at 2:15 and be forced to salve after all the damage you took. I would also note that any spawn with a satyr purge will make you take redicoulous ammount of damage. The problem with that is that you will turn your five stack camp into a 4 stack camp unless you want to wait until 2:51 which will basically negate the speed of SQH. So with SQH you will be forced to take 4 stack rather than 5 stack which will inherently make your farm slower because after the second double stack you will finish at 3:20 ish and you will have to another camp with out double stacking, unless of course you want to stand and with for 40 seconds. In this instance it is fine to give up one spawn because you gain level three and you will go to the large camps assuming you level up to four on the first large creep you kill.

However, If do the top 2 of the 5 stack, finish and realize that some one has warded the bottom three, and warding of these spots is exetremly common. You cannot double stack the large camp until lvl 4 because you just take two much damage and this will force you into camp at a time rather than double camps which is exetremely important when you are doing the large camp because you only get 200 gold + walk time compared to the 400 gold no walk time.

tl;dr: Stout shield + Queling blade + Healing salve is faster but is more riskier and really camp dependent.