I think Hellions are a mistake - partly because they cost too much for what they are, are not that good at what they're supposed to do, and as your only infantry at game start are going to absorb 100% of the enemy's long range firepower that isn't good for vehicles, and you'll lose a lot of points with every one of those wimpy dudes who whiffs his cover save.
Secondly, for my money, neither Wych squad is really built well.
The first one is basically only good at hitting vehicles...well, this is 'okay' if you're planning to split Vect from them and have him go assault stuff and them go assault vehicles, but at 2500 even Vect will probably need help with whatever he's assaulting, and those Wyches are, at best, fodder.
The second squad is the worse of the two for my money - they only thing they're built to deal with is GEQ and vehicles. I don't see the value in avoiding the Agoniser with them, as you're hamstringing their offensive capabilities.
My thoughts,
Thor.