I agree with what Geoff is saying but I will add this....
IF (and it's a big if) you're very drawn to the build of the Hensel and you are placing greater importance on the metal housing then you will be disappointed in the build of almost any strobe with a high impact plastic housing.
Having said that, it's important to realize that all Elinchrom strobes from entry level to high end have a plastic housing, Photogenic's and Norman have a plastic housing, and even the newer Profoto D1 has a plastic housing.
I don't see anyone complaining about plastics when it comes to any of those strobes or the various others that are not mentioned.
So it's up to you as to where you place importance and what you perceive as 'better'. You have to look at the big picture and think about buying strobes as buying a system that includes modifiers and accessories. You have to think about whether you want to use branded accessories or third party, and you have to look at the track record and overall performance of the strobes.
Hensel's are good, don't get me wrong. But they're no better than other strobes that have plastic housings and weigh a few pounds less.