On the plus side for stabbing yourself in MF2, you can continue to naturally regenerate with only half your hunger shanks filled, and it doesn't use up your hunger very much due to HungerOverhaul. This means you can sit there and fill your altar yourself slightly easier then I imaging it is in vanilla (where you're probably munching food all the time), if you already have your food situation in MF2 sorted out (Where I eat maybe once or twice per multiple complete refills of the altar).
Of course the increased costs for Runes more then balance that small benefit out (and some of the Sigils too, Green Grove is expensive too, 3 MFR Harvester, 2 Fertilizers, and 2 Planters, but sooooo worth it to watch your farm go into overdrive when you stand in it. I think the lava crystal was also increased in cost, along with the 2 Runes that boost Altar LP gain)
That's most of the differences in MF2-Blood Magic, mostly the same, just slower progression due to resource costs. Looking forward to trying out the Ritual of the F. Knife/Regen combo:
Question - will it fit under a tier 4 altar, or do I need do build the shape of a Tier 5 to make it fit? Cause I ain't farming Withers to make a real T5 any time soon.
Edit: Also if you try MF2, I really recommend enabling Ominous Woods in the BOP configs (disabled by default), as otherwise you are stuck waiting on the RNG for a Endermen to fight. Ominous Woods only allows 2 mobs to spawn, Endermen & BOP Poison Spiders, so you can usually get a fight at night if you find one (but being MF2 you'll want good gear to go out at night, or bosses will eat you).