That doesn't sound like a good solution at all. 1st, that formula is bugged, causing Cure Minor and Cure Light to both heal 0 no matter what level you are, Cure Moderate, a 2nd level spell heals 1hp/caster level, and Cure Critical Wounds heals only 3 hp/caster level (to a maximum of 60, okay, so that's slightly better than it used to be). 2nd, even with Wis or Cha mod to healing, that still means that the lower level Cure spells are even more worthless than ever, unless you're talking about Wis or Cha mod/caster level, in which case Cure Minor Wounds becomes a heal anywhere from 3 to 10 hit points/caster level for a 0-level spell slot, which is ridiculous.
You may be misreading the formula--it's level-1, times 2, per HD. I should also mention, in case it wasn't clear, that the CL cap is removed, since it's now dependent on target HD instead of caster CL. Cure Light is indeed 1/HD, since it's (1-1) =0 (counts as 1/2 as mentioned), 1/2 * 2 is 1. Cure moderate is (2-1)*2 = 2 per HD, max of 40 for a 20th level character. Cure Critical is (4-1)*2 = 6 per HD, max of 120 for a 20th-level character. Cure Minor is unchanged; in my view, it's there for stabilizing people and not much else.
Regarding altered healing potential of low-level spells, it makes healing slightly weaker at low levels (the levels where you're only 2 CLWs away from death anyway) but makes it stronger at mid and high levels (the levels where in-combat healing is currently a complete waste of an action). You can probably conservatively count on having around a +3 Wis modifier at 1st level, making CLW heal 4 on your 1st-level partymates, just 1.5 points less than standard CLW on average. At 2nd level, it heals 5, once again 1.5 HP behind on average. If you have an 18 or 20 Wis, you're actually ahead on average, and of course when the standard CLW caps out, this one keeps scaling. The first level you get Cure Moderate, it heals 6 (CMW on 3rd-level char) + 3 (Wis) = 9, vs. an average of 12 (2d8+3) for standard CMW. By 6th level, standard CLW heals an average of 9.5 and standard CMW heals an average of 14.5, while this CLW heals 9 (with +3 caster Wis) and this CMW heals 15; at any higher level, this version pulls ahead. And note that I left the add-on at the end up to preference; if you want healing to be stronger across the board, adding 2*Wis or +Wis + CL or +Wis + Cha or whatever instead of +Wis makes all Cure spells pull ahead of standard at all levels, and if you want natural healing to actually matter at low levels for whatever reason you can drop the +X entirely.
To clarify myself, it is elegant... for another system. The numbers need to be pretty high for that to work in D&D. Do you mind if I snatch that for my own use?
Go right ahead. Granted, the numbers could easily be higher; I wanted to use off-the-cuff numbers that used a linear scale and kept Heal, the spells I was basing it on, the same. If I were putting Heal at the top of the scale instead of leaving room for higher-level healing spells, I'd probably end up going with larger CLW numbers and an exponential function.
EDIT: Although, capping max number of hit dice healed by caster level might not be a bad idea. Prevents abuse from hiring a bunch of low-level clerics to follow you around.
Good point. I was assuming a cleric healing an even-level teammate, but as usual minions screw things up. Changing it to max(CL,HD) should work out fine.