I think he's at least stronger than the enraged power he displayed against Freeza. Why would he remain weaker after receiving a near death boost? Gohan's rage boosts are just his full power that his gentle personality inhibits anyway. Like Piccolo says, he only has to put his mind into it.
Vegeta even noted things were starting to look good when Gohan powered up too, so he ought to be fairly powerful. I bet he's on initial 2nd form Freeza's level, but not quite as strong as Freeza's powered up self.
As for where he maxes out, I'm not sure. I tend to flip on how accessible the power he displayed against 3rd form Freeza is. Was it a rage boost? Was the attack amplified?