I've bought the HKS Valcon kit but have yet to fit it. I guess an advantage of allowing the ECU to control the VVTI is that it can tie it in to all the other adjustments its making, whereas when you control it yourself via the HKS controller then the ECU is unaware of it.
The Valcon cam can apparently adjust to 272 on the intake side! What I plan to do is install the cam anyway, but not sure about which method I'll use to control it yet as I haven't decided on ECU yet. If the ECU can do it, then I'll get that to control the VVTI, but if not, then the HKS controller.
Apparently (and I may be wrong) but I've heard you can still use the HKS controller to control VVTI on the standard VVTI cam...
EDIT: I'm still undecided on whether I need an exhaust cam. I've read on the forum somewhere that you may not need to with the HKS intake cam, but it was a while ago and I can't find the thread.