Having all three be one-for-one is a nice idea, and it would be great aesthetically if it worked out, but the three resources work in far to different ways for them to be balanced preps.
A +1 mana prep will virtually never
get used, it'll have to be +2. The problem is that 14 mana is a dead zone; you can't do anything with 14 that you couldn't do with 13, and it doesn't give you an improvement to your potion effectiveness either. This means you have to combo it with some other form of MP increase to make it useful, but if you're packing other forms of mana increases, you probably don't want to waste a prep on a paltry +1.
The mana boost prep definitely
needs to be +2, otherwise it's useless. I feel the more extreme shifts were more interesting as preps because they allowed you to tailor your character according to your strategy. The problem was that the sacrifice was too high for two of the three tradeoffs.
Overall I feel like these preps have been watered down, and I liked their old more potent swings, even if two of them weren't very useful.
Also making preps have less of an individual impact means players are much less 'locked in' to a particular strategy; only nudged a little, with room to bail if the RNG turns up something totally contrary to what their preps have made the character.
Can't say that any of the old booster swaps were a "lock in" at all. If anything, they gave you more option to play different races. You could play a human with attack->MP to bring yourself up to the nice 15 MP level with no real effort, and non-human races had their versatility greatly increased by HP->Attack which let them be more competitive as high-level characters.
The way i see it, preps like these should give the player the sense that 'i am going to focus on melee', rather than ' I have to pick up a CYDSTEPP early or it's an instant restart'.
I don't think the booster swaps were ever remotely like that. Really non-dwarf Rogue is the only "CYDSTEPP or bust" character, and the current incarnations of Pactmaker, Binlor, Glowing Guardian, Jehora Jeheyu, and even Earthmother (in a pinch; she won't carry you through to the high levels...) all give him some alternate options for survival.