I'm a softimage user.
first of all thank a lot for this subforum dedicated to Softimage users.
One the best feature for my daily work are the great softimage workflow.
Tools like Move component tool are priceless.
For understand how good are softimage modelling tools, please, look video done by Vitaly Bulgarv:
http://www.youtube.com/watch?v=4ct9voyU3h0 [youtube.com]
His modelling process, and softimage tool are well explained in this tutorial:
http://www.thegnomonworkshop.com/store/product/544/Character-Design-and-Modeling-for-Next-Gen-Games#.UxhEWoWafHQ [thegnomonworkshop.com]
Whatching this tutorial well explain, better than words, why and how softiamge modelling is so great.
I love softimage for simple and fast workflow and because is a complete tool for a freelancer, not only VFX, but great modelling tools, efficient rigging skinnig and rock solid viewport.
Now, from my previous test done in Houdini I found it a bit overcomplicated and not efficient in modelling side. I think you need someone to show the pro of your modelling tools, a good, advacend tutorial explaining houdini workflow.
The other great tutorial of softimage is rigging, but I never test Houdini in this field.
For ICE, I think here Houdini has very great offer, but again, I never investigated this in Houdini.
Another consideration: your annual upgrade plan is a “bit” expensive compared to ADSK