Hey All, been on the Naish gear for ever. Started on the 1800ha, then 1400, now predominantly on the 1240 (I'm 95kg). The 1400 will feel very similar to your 1800 except quicker/less draggy, and only marginally less glide, but pumps easier so its easier to keep going. The 1240 you will initially find quite slippery, but once used to it, it's extremely efficient, and on a short fuse will turn awesome. I pretty much only use the 1240 now, and I'm getting up in lighter conditions than with either of the other two using a 5m wing. I'll be getting a 1040 or 914 for the super windy days, or bigger swells.
It'll depend on your skill level as to which way you decide to swing ??

Thanks for replying. I will go with the ha1240.

Tried it today.. Very nice..

At 80 kg I would go the 1240.
I'm 95 kg and love this foil for winging.
Having said that have the 1400 as well and is a great foil. Also have the 1050 surf and although can't compare due to size difference, no doubt that the surfs have way less glide and pump than the HAs. The 1240 Ha is surprisingly agile.
Nash hasn't overdone the HA ratios on their HAs like some other brands, not to be mentioned,IMHO.