Recreate a (simple) given model in iges

Hi all!

Been following the forum for a while now, subscribed today to see if I can learn something extremely specific to my line of work (chairs).

I'd like to know your take on my issue.

I attached an IGES model (made in rhino) I'd like to recreate as faithfully as possible (nevermind the mounting bosses).

Featureworks is greyed out no matter what I do (also disabled 3dinterconnect).

The loft I made in the part is not close enough to the desired result.

I tried offsetting the superior face, extend it to regain the width lost with the fillets and extrude the whole thing, but I have a "blue edges" trouble with consequent failing fillets that I can't seem to be able to solve.

My goal is to recreate the model just so I can add a shell at 2mm from the bottom surface. I managed to do this in a very similar model to the given one, but I really don't manage to work it out on this one. Therefore I decided to rebuild it from scratch in SWX. 

Now, I'd like to know if there's a much simpler approach I'm not trying..?

Might it be the IGES is not as tight as the last one where I managed to achieve what I wanted. I still would love to know how to rebuild it.

Thanks a lot for your help! 

SolidworksSurfacing