I don't worry much about whether any d20 class or genre is good in the "higher levels". For me d20 totally breaks down from anything I'm interested in playing after around level 12 and doesn't work. It's not really a concern in most of the campaigns I've played in any case. My longest running campaign currently has been running for three years from level 1 and we're just now reaching 8th level. I expect to run Midnight from around 3rd to 10th level over the next three years. I expect Channelers to be perfect in this range. If a DM found any Class lagging at whatever level the campaign was at, I would expect a good DM to compensate - there are talismans, etc., that a Channeler could have to ameliorate the amount of spell energy of the higher level spells.
I've looked at every published setting that's come out for 3.X ed. For my money, Midnight is the only non-homebrew setting that's captured my interest (and money).
I've looked at every published setting that's come out for 3.X ed. For my money, Midnight is the only non-homebrew setting that's captured my interest (and money).