Hi Domdino,
I bought the 150 this summer (I wished it was 140..) and had a blast with it on my vacation to Corsica. Well you know how the 150 is. Used my 6m P3 a lot (great wind and waves)
I also travel once a year to family by plane… so when the 140 came out I ordered one..it would be better for travel and even if it got 85% performance of the 150 I would happy..
It took a while, had a family visit without the 140 (but I didn’t get any wind, so it didn’t matter), but then it was there..
A bit improved straps, nice graphics (though I loved the looks of the Mako 08 range). But after I had the 150 I really didn’t care about the looks anymore (as long as it got some red or orange in it, which I think is better for visibility), its the ride that counts!
I used the 140 once so far, with my 8 and 6 m P3. The board will not have the same drive as the 150 but it is really close.
The 140 is fun to ride, toeside-heelside switching by sliding and jumping is really easy. No whip tricks are possible but when i really want to go for that I take my 666. The 140 doesn’t spray, just like the 150. Going fast, no problem. Carving?.. Mako style !! It is a little bit more sensible for nosediving when you push it, the 150 almost could not be nosedived by me (67kg clean..)
I think the 140 is a bit better ...
Don’t know if I’m any help.. but you really won’t be disapointed in the 140, get it… 
Sunday we get some wind again, can’t wait ..
Regards,
Arjan