To turn this into some numbers, a 20th level sorcerer has 6 slots of every level.
With a reasonable caster ability of 30 that's 3/3/2/2/2/2/1/1/1 bonus slots.
Counting 0th level as ½, the total power (SL x capped CL x slots) is:
½ x 5 x 6 + 1 x 5 x 9 + ... + 9 x 20 x 7 = 5,380.5
For the 20th level psion there are 343 PP plus 100 PP. 443 / 20 = 22 (3 left).
2 x 3 x 1 + 10 x 20 x 22 = 4,406
That's about 20% more total effect for the 20th-level sorcerer in a day (above example is at 10th level, where numbers are a bit different, of course), but to take advantage of that, the sorcerer has to cast the whole 77 spells! How often would that happen? Almost never, I suppose.
On the flip side, at this level, the psion can manifest 22 powers of a 10th spell level equivalent!
The sorcerer has 7 spells of 9th level, 7 spells of 8th level and 7 spells of 7th level only to compare with those.
And to get to the same 4,406 total effect, the sorcerer will also need all the 6th level and most 5th level spells in addition to that; not to forget the extra actions needed to cast them.
Sure, there are still quite a few 0th thru 4th (and even some 5th) level spells left then, but what good are they, if you almost never get to use them?
The psion's speed advantage, however, is always there, and even moreso at high levels, where this is about the most important quality.
Bye
Thanee