I was affraid of this. I suspected gear would be influential on the HP gain, but I couldnt be bothered to test it (Im somewhat burned out on shelter). Its not like my casual-game dwellers NEED the extra +3-5 endurance points from gear, but it pisses me off that I missed out on roughly 100+ dwellers NOT being levelled while wearing the best endurance gear (I sent them out exploring to level, usually with whatever gives them 11 or more endurance).

Whoever designed this dropped the ball.

It doesn't matter how you get the level, the HP gain is applied based on the endurance stat with endurance mods.

Would any of you guys recommend using Sturdy Wasteland Gear (+5) to venture in the wastes? I feel since it's not a legendary item it might be replaced for another rare.

You can't get legendary gear from exploring. Only lunchboxes give legendary gear.

Right. What I'm wondering is if I send out a dweller equipped with a Blue item (Rare) like Sturdy Wasteland Gear, will it be replaced for another Rare? For example, Survivor Armor or Advanced Lab Coat.

Hasn't happened to my dwellers as yet. I think the explorer only swaps gear if the new gear has stat value higher than the one worn. So if dweller already has rare (i.e. total stat increase of 5), then new gear will need to be 6 or more.

Cool; thanks Ank. Hopefully he doesn't find anything that risks his Endurance.

What I do is train all of my level-one dwellers up to all-10's, give them some endurance gear, and send them out with the best gun I have available and 25 stimpaks. In about a day and a half or so they'll be level 50 and loaded with loot, so I bring them home and have them replace someone in one of the 2nd-floor deathclaw deathtrap rooms.

I work my way down the vault, replacing people with high-hp superdwellers able to wipe out the molerats.

I really hate molerats. Deathclaws aren't half the trouble of molerats.