I have 3 cities:
1 in S&D - doubt very much that I'll finish the event due to lack of space, negative population and can only upgrade 1 house - again a space issue, scouting times are 3 days so hoping not to end up relying on a scout coming in
1 in Woodelves - should finish the event fine but not in a hurry, plenty of available space
1 nearing the end of Dwarves (3.5 techs to go) - should finish the event fine but not in a hurry, some available space now with maybe a little more as I won't have got many, if any, Fairy buildings down before the end of the event.
As for other events of this nature I'm not bothered whether I finish or not, I won't be opening any eggs until nearer the end anyway, the small city will then be in Fairies so the rewards will be better. I know there will be the usual complaints of how it isn't fair that those non-diamond players will be unlikely to get to the 3rd grand prize, but I'm ok with what I get because free is still free.
I would say its hard for those in S&D where space is already at a premium, but it doesn't necessarily follow that none of us can get far because of it, not everyone has used every available corner in order to accommodate guest race buildings.