Myself I very rarely use 100% damage buffs like Inner Vision in PvP, It is just too easy for my opponent to avoid. But if your opponent lacks any evade move a Inner Vision buffed Soulrush would be gold. But using Inner Vision you really need Soulrush otherwise you might as well cast Beam twice instead.
With Punch you can surprise any Dragonkin trying to take out your magic trader, but I think Beam in general is a better choice(unless you keep running into alot of mechanicals).
Both Soulrush and Life Exchange are good abilities and it is really up to how you plan to use your trader which one you want to chose. There is no right or wrong here, only bad match ups.