I didn't notice any issues with power in South Africa (Rand Airport, >5000ft asl) in the R44 except to just keep an eye out for it during take off and landing, but the R22 has its work cut out for it and this was in spring when it was relatively cool.
You couldn't just climb vertically in the 44, (especially with more than 2 pax) you'd want to use your best performance profile.
Had issues with one of the R22s overheating a lot during IGE hover, but that was mechanical. You do have to keep a close eye on MAP during hover exercises though, there's very little extra power to pull if both pilots are near 90kg each.