Chris T., about informaton on the Elan 40 and Elan Impression 43 I suggest a download of both boat tests at http://www.yacht.de/yo/powerslave,id,10,nodeid,10,ps_lo,.html
that''ts the site from the biggest and in my opinion better Europe sail magazine. It''s in German, but you can use an Automatic translator (fron Google, for instance).
Normally they publish graphically the complete stability curve of the boat, and that, if you know how to read it, says a lot, specially when combined with information on the speed of the boat in several points of sail (given also graphically ).
There you can also download several other boat tests, regarding boats that are close to the ones you are looking for, like the Wauquiez Centurion 40, the Confortina 42, the Dehler 39 and 41, the Dufour 40, the Grand soleil 40, the Hanse 41, the Malo 39 and the C-yacht 11.30.
Each download costs 1,5 Euros and are in PDF format, with lots of photos, drawings and graphics.
First you have to fill and send the "Click and Buy" file, and then it is easy.
Hope to be of help