I have done some E6 PrC arena with Recharge Magic.
Metamagic only increases the recharge time of SPECIFIC recharge time spells, specifically each +1 to the effective level of the spell doubles the recharge time.
Here's the thing about specific,
Most spells will a specific recharge are either long duration buffs (Mage Armor), out of combat type utility spells (Plane Shift), or conjure something for a long time or permanently (Web).
Buffs being most critical, what happens is that typically you can continually hold a buff at caster level 6th, where duration = recharge time. Extend becomes almost pointless. Chain Spell becomes only a higher level option for continual buffing.
You're simply not going to be able to double teleport without a wand or scroll. In effect, casters that rely on repeated use of the same spell get nerfed a bit.
General Recharge Spells
Cloudkill & Quickened Magic Missile would put your 5th level spell slot on recharge. Same random recharge time.
I find I'm more inclined to use Quicken more than Persist metamagic, due to the reduced cost, and recharge bringing the slot back anyways.
You're right in that you may not have spells recharged in later rounds. For highest level spells spontaneous 1d4+1 (2-5) and prepared 1d6+1 (2-7) rounds. Casters can't nova highest level spells back to back. However, once you have 3rd or 4th level spell slots, you'll usually have at least one spell level available.
Personally I appreciate nova being toned down. The smart caster does their encounter or two, blowing their load and then hide in their demiplane. It's not possible for them to chain those spells, and now it's no longer a 5 minute work day. So, it encourages smoothing out daily adventuring.
There are other things that could be said about how it affects world economics, but I'll leave that to your imagination.
Overall, I feel like recharge magic narrows the gap a bit between spontaneous and prepared casters.