While Junktown is definitely pretty similar, It's not an exact match. Junktown exists in the world of the demo it's mentioned.
I also didn't mention one of the guys(can't remember if it's the guards working for a gang or the peasents who want them both gone) offers to give you directions to Necropolis. (Which would be moved to Bakersfield as it exists in universe and where the 'NESW' directions characters give you and the Mutant Invasion suggests it is). So that would be added, you get the map marker for Necropolis if you complete the Scrapheap quest. I guess a backup option if you ignore the Merchants.
Plus Dogmeat would be moved there so Junktown doesn't have two companions.
Difficulty curve wise it seems fine, slightly harder than The Hub(albeit the Hub has a pretty wide curve) and easier then the Super Mutant fight in Necropolis or beyond. Closest is probably the Liberation of Adytum in difficulty. Seems all about correct, there's one or two minigun guys, but they don't have the best armor and limited ammo, harder than the mooks in Junktown or most of The Hub, easier than the Super Mutants.
Sort of like the Khans Camp in a way. Both are harder than what's immediately around them, but not by a ton or anything, both are combat centric, and both warrant some neat rewards. A combat focused build and a competent player can handle the Khans after Shady Sands and Vault 15, a less fighting centric character may talk their way out or come back after they've reached The Hub. Like I said, the Midgame could really use something like that as after the Khans there isn't another large combat centric area til the end of the game. Plus you could always puss out and take the easy route, get some minimal gear upgrades and Dogmeat and miss out on the maximum loot and Necropolis tip.