What Sander said. Responses from individuals here (e.g. ARCB) will reflect their boats, and have nothing to do with yours. Having the information might allow you to to figure out which of us to sail in company with if you want to be sure of getting somewhere first. Otherwise, it's like discussing apples and cumquats. On a beam reach most boats are going to get to hull speed fairly easily and their length will determine their speed. Myriad variables (sea state, weights, sail area, hull shape, sail condition, rig...) will affect upwind performance to such a degree that comparisons won't be very meaningful.
I've always though the "no schedule" line was lazy. There are entrances you don't want do at night, tides that can help if used properly, and weather to be outfoxed. I wouldn't leave into foul whether or follow a group, but I do need to know how long a passage will take.
Generally not less than 5 knots. I would probably motor. But it doesn't take much for me to reach 5 knots, and with the reacher I can top wind speed. Even with my cat, I expected a high percentage on many courses. With a little wind, most of my boats would hit 10 knots on any course other than windward. If possible, I adjust my itinerary and schedule to avoid tacking, since VMG is a lot lower, though I don't mind beating.
But over all, door-to-door, I figure on about 6-7 knots. I've done a lot better, and I've done a lot worse.