[blykins]

The jist of it is that you want to make absolutely sure that the lifter you're working on is on the heel of the lobe. Now if you can guarantee that you're fine, but I rarely see a scenario when you can set both valves at the same time when that piston is at tdc.

I've seen that method vary by a decent amount on a solid cam compared to the Evo/ivc method. It's not that critical in a hydraulic cam engine but the same theory applies. Your cam has a good bit of overlap and there's more of a chance that both valves are not closed at tdc.