Yes, Wouter, Everything and anything.
That is a bit too much to type up here I'm afraid. In case you hadn't noticed yet, my posts are nowhere as long as in the past.
The specs you can find at the following link :http://www.watersportverbond.nl/data/Z8F_numdet-01-4-02-2007.pdf
All the values given in the listing are independently measured by Texel officials.
Personally I think the Nacra 570 is the better choice of the two. Both boats are about the same speed as indicated by the Texel handicap system, but the 570 is a less complicated boat.
Also the 580 must be expected to be 30 kg heavier, and it feels that heavy on the beach as well. I have lifted it.
The nacra 570 is 2.50 mtr wide (Again Texel measurement) and the nacra 580 is 2.60 mtr wide (Texel measurement)
2.50 mtr = 8.2 feet or 8 feet 2.4 inches
2.60 mtr = 8.5 feet or 8 feet and 6.3 inches
This data if supplied among many other in the compressed excelsheet which has a link on this page http://www.watersportverbond.nl/content.asp?me_id=468%20
This sheet contains ALL measurements taken by the Texel officials such as exactly sailmeasurements used to calculate the overall sail area. It is somewhat difficult to read but with help from the webpage on what is what you can.
Anyway, the 580 is the same widths as the F18's and the 570 is the same width as the F16's and 4 inches narrower. The last is the legal trailer width in all countries around the world.
The rigs are almost identical, with the exception that the 570 has a boom less mainsail.
Both boats are modified from the original designs Nacra 5.7 and nacra 5.8 and both use alot of parts of the nacra F18 designs.
Personally I feel the Nacra company has the best line of boats in the way of Nacra 500, Nacra 570 and Nacra Infusion F18. I'm not very impressed by the other boats they bring out. The three I named all are well balanced boats that strike a very good balance between different desired and limitations. The others I find less attractive in this sense.
With reasoning I really do like the nacra 570 as the better option of the two and I'm just convinced that the 570 with a spi will be an excellent boat to have, it will be very fast downwind and still have good upwind performance. The only downsides of the 570 in my opinion is the boomless mainsail (I think booms allow better sail control) and the fact that there is no active racing class for it like the F18's. The nacra 580 is heavy, not much faster at all, more complicated, noticeably harder to lift the bow (because there is no skeg to act as a fullcrum) and even more unpopular then the 570 as a racing class.
570 (and 5.7) sailors at my club like their boats, the single 580 owner is rumoured to look to sell it and get a different type. We have several 570 (5.7) at my club.
And specifics you want to know ?