I don't think we need to push it out that far. Deliberately ignoring July and August as too hot and holiday season, we don't currently have that many tastings planned this year, with nothing in June, (July, August), September or the first half of October. It would seem better to me to have a tasting even if one of us can't make it rather than to defer it further; and I'm sure come January we'll be needing a 60@60 tasting, never mind a major 70@50 horizontal, and I'm sure others
Ignoring July/Aug given heat and holidays, and taking into account that in late June some may be in Porto for São João, and late Sept some may be in the Douro for the harvest, so that still leaves the first halves of June, Sept and Oct clearly available this year. I appreciate DRT's efforts to find a date which suits us all, but suggest that notwithstanding previous posts, DRT as organiser now sets the date as best suits him in one of those ranges (and if I or others can't make the selected date then so be it, but at least it goes ahead for most folks).