No, this won't be another thread about 40->25 man problems or rolling shamans and paladins:)
I'm interested to hear views on 2 other topics on my mind.
1) Would you want your guild to continue to raid (but a smaller number of days) during the leveling period from 61-70? Or just stop all raids until many players are level 70?
On the one hand, I'm eager to see new content, and leveling asap is probably the most efficient way to strengthen the guild from a min-max perspective, bringing the level 70 10-25man content more quickly into reach.
On the other hand, I'm afraid that stopping all raids totally would take away what makes raiding guilds 'click' in the first place, even if only for 1-2 months. For the 99.99% of guilds who haven't killed Kel'Thuzad by then, it might also mean that they never, ever get to see whatever content they skip in AQ40/Naxx (the RvR for these zones looks to become pretty horrible as guilds downsize for 25-mans. Basically now or never)
2) Would you want your guild to do a partial/total reset of DKP?
DKP rewards past attendance, but at what point does past attendance count for less? With the lvl-70 5-man instance drops rivalling T3 drops, is it really still fair to penalise newer players so heavily for not having helped farm the guild's T1-3 sets? Wouldn't newer (relative term - its possible to be in a guild for 3+ months yet never be able to catch up DKP-wise) players be better off joining a guild that started with a clean slate for DKP?
On the other hand, there is also a correlation (imperfect, I know) between player DKP and reliability, as well as to a lesser extent, experience and skill. Its normally a bad move to alienate the core players.
Naturally, the best answers to these questions could change a lot when we find out exactly how long it takes to level to 70 (current estimate: 1-2 months first-time through for 'normal hardcore' player), and how the level 70 5/10/25-man drops compare to T3 (blue post suggests equivalent to best 5-man drops.)
1 - Stop everything and go lvl and explore the content. The Xpack will be just like starting on a new server, raiding won't start till you have enough lvl 70s ready to go. There's no point in continuing to stay at lvl 60 in Naxx banging your head against the same content when you could just go back in a couple weeks with lvl 65s and breeze through more of it. Also no point in depriving people of all that new content.
2 - I advocate a total reset. No tellling who is going to still be playing, will make the lvl grind in time, will even buy the xpack. Not to mention that some raid roles are totally changing and with everyone picking up shaman/paladin you'll want to start those new classes off at a fair balance with your guild.
As for your comment about the T3 gear and 5man instances, Tseric posted saying that T3 will be the initial "entry level" raiding gear at lvl 70. He said he'd be very surprised if anyone replaces more than a couple of pieces of their T3 items before hitting 70.
1) We haven't reached an official decision, and won't until we see what's out there, but most likely maintain take a couple of weeks to run around by ourselves then back to Naxx (and any levelling raids that may be in the game) once or twice a week so we can finish it and so we can kit-out in better gear to level in and to start out our level 70 raids in. Becomes less important if we can get equivalent gear in level 70 5-mans, of course, but I doubt we will for the most part.
2) Start a completely new slate at 70 for sure. It's a pity in some ways we're a fixed price guild... the DKP burnoffs in the next couple of months would be spectacular otherwise.
I'm going to push fairly heavily for my guild to at least still clear AQ40, because while the raiding gear will be nice for a lot of people, most of the healing classes can really use the hybrid/grinding gear from AQ40 more than they need more healing items, so it seems only fair to me to continue to clear that as well.
Of course, Naxx will be done as well, but how often remains to be seen. Fights as 62s even will be a lot easier though, and given most of the talent trees we've seen so far it looks like just getting the 41 talents will be pretty huge.