I'd be willing to do a specific character's voice or two. As long as someone edits the audio there's no reason it has to be recorded sequentially. (If anyone wants to know what I sound like, I did the voice of Meri Lin (first voice heard) on this Youtube commercial for a friend's webcomic; it's not a good-quality recording, and the timing was awkward to pace with the video so I think I sound stilted, but there it is.)

For a while I had a dream of having a different person for every major character, but for an amateur project this presents many problems. The first being geography, it's unlikely we can all meet in one place for this. The second being scheduling, it's hard for many people with other full-time obligations to meet regularly and consistently without "it's my job" working as a good excuse. The common response/solution is to have different parts recorded separately and sent in to be recombined, but that leads to two new problems.

First, tone. Without people there in the same room to play off each other the different readings can be jarringly out of character with each other. Secondly, it's vastly more post-production to recombine everything (which I'll get into next).

Alternating chapters would be great, but I think I'm going to decline for now, partially for the reasons you mentioned. Having a consistent tone is probably a good thing, and I would have a very hard time telling someone I couldn't use their reading. For someone to spend $100 (or more?) on recording equipment and several hours reading and be then told it's no good seems... cruel. But also for two other reasons (I'm all about two's today)

1. Post-production. This is the majority of the work. It took me about 2 hours to put together the 17 minutes of the pilot. I expect this to go down drastically as I get better with the tools, but post-production will always be more than half the total time spent because I have to go back and re-listen to the audio in it's entirety while pausing repeatedly and making tweaks/changes/removing flubbed lines/inserting clips.

2. Reading is the fun part. I really enjoy the actual reading into the mic part of this. :) So while it's time consuming, it's something I would consider to be fun in it's own right. If someone else were to send in audio of them reading then I still get all the work of post-production without the fun of reading aloud to compensate for it.

Hopefully this isn't burning any bridges, and in the future if I'm able to work things differently or realize I really need help I'll still be able to come back and ask for some. I do appreciate the offer.