How far would (edit: ) a guild that just barely made it through Sunwell (/edit) get in to Ulduar if it was out for six months and the original ilvls were used? Post-nerf bosses and the 3.3.5 class balancing or whatever classic will be launching with.
I tried for 30+ minutes to find parses from...legal...places but couldn't find any. I have a hunch that hardcore players crush even Yogg+0 shortly after release, but I'm not the least bit sure. But that fight in particular is a lot of experience in avoiding sanity-sapping skulls.
For reference it looks like 4000 US guilds cleared SSC & TK and 2000 US guilds cleared Sunwell according to the progress page on warcraftlogs.com
Oh and historical data on Algalon kills would be amazeballs.