Actually, as much as you might be down with time travel, the dual dimaensional thing has me down as well - the Thomas Covenant the Unbeliever series filled me with that dual life/fantasy stuff.

If Parson returns, I would rather not see his story continue other than an epilogue. The scene where he cares about his 'pawns' as you pointed out, would be a nice finishing touch, but that's sufficient.
I find, though, that us learning more about Erf, or Ark, is much more interesting through the eyes of a stranger (Parson's) than through another pair that is morew famailiar. And to spend another few strips to situate another individual, who then would have to learn the rules again, summonned somehow, again, would be redundant.

Parson's adventures will continue in Erfworld, with or without time travel. Unless... the story becomes more skewed from Charlie's perspective, and Charlie becomes the protagonist somehow...

In either case, I look forward to what the Arkencreators have coming.
:)