Fourth player:
Agreed we should get a fourth one - and I think a Recruitment thread should be opened. I will not recommend anyone because... I have done so in the past, and the results are not necessarily the best ones :P
Continuity:
This is a tricky one... I am a huge fan of Magus, and could easily stick with Hedrak for the future. But I think dungeon delving implies further considerations like Norde pointed out - there are some roles which can make a big impact on the whole thing (and scouts are one of those). So there may be the need of a more balanced group. In that case I am available to reshuffle and create another character.
Gameplay:
This one is even trickier, and will elicit also questions from my end :D
Will this be basically a staging ground to 'mechanically' test characters against certain encounters? Or will there be relevant story elements revolving around it?
I ask because, even though I am a HUGE fan of dungeon crawling, challenging encounters, along the lines of 'slogging through the Underdark' or braving Rappan Athuk, I usually do not find myself very motivated when the game turns into simply a series of mostly unrelated encounters. If that will be the case, I think I will step out, and leave room for another. No bad blood, no harm done, but I do know myself, and I don't think such game will grab me. Funny enough in the past I was happy even just participating in 'arena' like events, where you overcome one challenge, level up, have a next challenge and so forth. Nowadays... I need more :)
I am not intending for a series of disconnected encounters. There will be some backstory and other flavorful elements. There will be overarching coherence such that the different components fit together and don't feel strung out or random. There will also be a structure (when I use the word structure, I'm talking about things like flowcharts) which creates a sense of working through different challenges and making progress.
Edit: also, my philosophy is that player skill should be rewarded and that testing your ability to build a powerful character is not interesting for very long.
So like a White Plume Mountain sort of thing, where there is an overall goal and story going on in the dungeon then, that sounds great.
@Hedrak - Norde and I are doing a lot of brainstorming for new characters/builds on discord, although it may be a little bit of a read to get into at this point. We would like your input so we can know what to build around.
I noticed ;)