I don't know Helium but I know very well Zephyr. I had this kite for 4 years and I sold it last year for to buy a Flysurfer Soul 18m.
I love Zephyr, really good kite in light wind with a great windrange. You can ride from 10knt to 20knt with a twintip (I weight 68kilo), very good depower. Good hangtime, easy to learn new tricks in light wind in 12 -15knt.
Under 10knt you must take a great board twintip and you can ride with 8knt but it'snt possible (or difficult) to jump. There is 27m line but under 12knt it 'better if you put 3m more.
This kite is really good for freestyle, oldschool but not for surf or foil. I think Helium is very good for foil.
The pressure in the bar is a little strong.
It s depend your programm :
Foil : 'd rather Helium
Freestyle / freeride : Zephyr