D&D 5E Short Rest Mana Point Spellcasting (+)

[Xeviat]

For a while, I've been working on a new spellcasting system, and since I have a new game going over Roll20, I've been compelled to work on it some more. I have been 3E style scratch building NPCs, and found them a lot easier to build when I didn't give spellcasters access to all of their spell slots (easier to estimate CR too without assuming them firing a lightning bolt every round). I've also been wanting to have the game on a short rest timer, to make balancing encounters and pacing adventures easier.

I've long wanted to use spell points, so along with the short rest recovery mechanic I'm calling this my Mana Point system.

So here is what I've been working on. Below is the current DMG spell point system's spell costs:

Level	Points
1	2
2	3
3	5
4	6
5	7
6	9
7	10
8	11
9	13

And here is my proposed spell point progression based on caster level (including the difference compared to the base system). It is shown side by side with the old spell point progression, and what that old progression would be if you divided it by 3 (for 2 short rests and 1 long rest):

Level	Old SP	SP/3	MP (2/level)	Difference
1	4	1.33	2	+1
2	6	2	4	+2
3	14	4.67	6	+1
4	17	5.67	8	+2
5	27	9	10	+1
6	32	10.67	12	+1
7	38	12.67	14	+1
8	44	14.67	16	+1
9	57	19	18	-1
10	64	21.33	20	-1
11	73	24.33	22	-2
12	73	24.33	24	0
13	83	27.67	26	-2
14	83	27.67	28	0
15	94	31.33	30	-1
16	94	31.33	32	+1
17	107	35.67	34	-2
18	114	38	36	-2
19	123	41	38	-3
20	133	44.33	40	-4

So, my structure ends up being really close to the core spell points when used conservatively. The ability to nova in one encounter is severely limited, flattening out the power difference between casters and non-casters, and making it easier to balance short days for slower paced games. At its biggest gains, a character may have 1 more 1st level spell per short rest, and the times when my system is granting more SP than the core system is in the beginning (except a little hiccup at 16th level). It even ends up a little behind.

There are a few parts that need to be worked out:

1. Healing Spells: The base game has some short rest healing (celestial warlock, healer cleric, fighter's second wind), but aside from the warlock it's fairly limited. How will that affect the game if a two hour rest fully heals up a party (one for healing and one to regain spells)? What other than time/exhaustion rules would force a rest? I'm not sure I want to go all the way to a Wound/Vitality system.
2. Highest level Spells: The SP system in the DMG limits how many times you can cast 6th level spells and above to 1/day. Such a limitation seems prudent, like the Warlock. Would you rather cap SPP at 20 and then add in the high level spells, or have it continue to scale and just have casting high level spells drain your SP a lot more? That would still leave nova potential to blow through your 9th-6th level spells in one fight, but that would cost 43 MP and not be possible. And someone can already do worse in the current game, so that would already be a limitation.
3. I'm sure there's other things that will need to be addressed. Like how will abilities like Arcane Recovery work (probably an extra daily pool of MP)? I'm sure there's other abilities I'm not noticing.

Also, I'm probably going to merge the Sorcerer and Warlock (mostly warlock in mechanics, I'll probably rebuild metamagic into feats) and then work on adding a Mystic to my game. My Monk will be treated like the half-caster version of the Mystic (that one's almost done, but I stalled on it when everyone was saying the current mystic is OP).

What do you think I should watch out for?