Old inferno similar to mp2 or 3 is probably true. The HP is prolly similar, but damage is slightly lower now. BUT that's not the point. Everyone's rocking 180-200k dps, and some are rocking over 300k. We didnt have those gears back then.
You know what was considered godly weapon? 850dps 80+chd and socket. If it came with dex, it's UBER godly, if it came with dex AND vit, OMG!! Sell the farm boys! If somehow someway that thing had LoH, OMFG, sell your neighbor's farm too!!! Like one of the above posters stated, 50k dps was damn near impossible pre 1.03. ONLY a few had that. Post 1.04 50k dps was considered a 1,000 dollar monk? I remember trying to sell my 43k dps monk pre 1.04, and i got offers of about 100mil. And the buyer ended up buying a 65k monk for 500mil gold. Back then gold was selling for something like 3-5 dollars per mil. So essentially he paid something like 1500 dollars for that monk. Today 65k dps monk is a sub sub sub sub sub budget set. 850 dps with 80chd and socket is pretty standard weapon.
So again, you cant compare mp lvl vs old inferno without considering gears. The feel is prolly about right. MP10 is like old inferno act3. Most cant touch it, even if you can, it's pretty hard. The only difference is, I think old inferno doesnt take as much time if your ubered geared. SB runs went pretty fast, and bosses didnt have 300mil hp while your only rocket 300k dps. In comparison 60k pre 1.03 monk didnt have to face a 60mil hp Azmodan. But stuff did hit a lot harder, and affix got nerfed nerfed and nerfed some more now. MOLTEN was the mother of all. I remember pre 1.03, when i see molten lasher packs, I would kite them to dead end and just die, didnt even bother attempting cause it's pretty damn near impossible. Even act2 spiderlings molten packs were hard as hell.