I was considering using a variation on HP progression for my up coming PF Campaign but i realise it will alter the game balance a fair bit so was looking for educated guesses or actual experience of the affects on a game.

I like that 4E PCs start with more HP and you can throw a tougher encounter at the party straight away, instead of sending tiny groups or individuals at them. BUt i don't like that a PC at higher level can basically fall off a clif and walk away from it (when rolling damage dice only and not giving PCs narratively accurate injuries).

So i was thinking of running an HP system which give the PCs a max dice plus their con stat as starting HP but only gives con bonus plus a very small dice or set value at each level.

That would be something like: 1 HP + con bonus for mages (and anyone using D6s), 2 HP + con bonus for Rouge/Cleric or 3 + con bonus for fighter types. Or: D2+con bonus for mages, D3 + con bonus for clerics and D4 + con bonus for fighters.

The good thing is that a DM can match the party against, probably, twice as many monsters of CR1 or less straight away and have dramatic battles right away (cause i don't think 4 PCs fighting 3-4 Orcs is very impressive).

But it will probably mean that as the PCs level they will not stay even with the CR of monsters. Which means that either monsters HP could be lowered a bit or a lower CR encounter would match them, in turn saving higher CR creatures for even higher charcter levels. I'd lean towards the second option.

Allowing the PCs to gain +1 to 2 stats each 4 levels, more like 4E could help to make them maintain parity with CR and allow a PC to be more diversely developed.

It might mean magic item distribution and treasure allocation should be altered a bit too.

Has anyone tried this or have enough experience with the game to have an idea how it would play out?

Some how a slower HP proggrassion strikes me as leading to more tense combats and a more agreeable game style (for me atleast).