It's not really new, but something I like to keep people aware of is the Ardent, and his
Alternate Class Feature to choose within reason what powers he can add to his mantles. Not only can you add, but you can Substitute also. Don't like the 3rd level power? Get rid of it, replace it with something better/more appropriate. You can be as practical, or theoretical with this as you wish.
Now, within reason is something that obviously needs to be interacted with your DM, and I can't make a comment over what your DM can or cannot expect. Most people are pretty okay with the idea of putting any Psychic Power to fit the theme of the mantle. Many (most?) mantles don't actually include 9 powers, so you've already got the leeway, but as mentioned, you can substitute if you wish.
Where this gets
fucky, is when you include the abilities of a Spell To Power Erudite. Now, I'm sure many of you think "oh, it's just a Spell to Power Psion, we know all about that", but it's the fact that unlike other StP shenanigans, you don't need the StP Erudite present. (Technically, the Expanded Knowledge trick can do the same, but until you turn epic, that limits you to 8th level spells). However, Epic Manifesting and Epic Psionic Powers are treated in the same manner as spells, effectively Level 10's. This means that all that's needed is an Epic StP Erudite who is able to Manifest Epic Powers, which would let him learn Level 9 Spells as Powers.
Combine that with Divine to Arcane tricks like Wyrm Wizard/Recaster, and suddenly, every spell, Ever, is theoretically an option for a Spell to Power Erudite. Because of the existence of spells like Travel Through Time, and planes with non-typical time traits, this means that as long as at some point in the games setting, an Epic Spell to Power Erudite (or multiple) who have managed to learn every single spell and turned it into a power (it doesn't have to be that one dude, but there has to be at least one Epic StP capable of Epic Manifesting, who collectively have turned/will turn every spell into a power), you can select it as a Power Known.