When 5.2 was in the works & we got the dodge/parry addition to Grand Crusader, Theck did the
5.2 Smoothness Simulations which ran a range of gearsets that included a control/haste (i.e. hard cap'd then haste) and a pure haste (500 pts hit/exp & everything else piled into haste).
The SotR uptime in those sims is directly linked to the HoPow generation of those gearsets. Control/Haste maintained the highest SotR uptime, with Haste coming in behind it.
So if haste did provide higher holy power gen than cap-then-haste, you'd be right... but it doesn't, at least based off the data I've seen so far.
The point about SS speed is an interesting one, because SS wasn't included in those sims (and obviously enough neither was SoI, considering we haven't got any information on that yet). So you may end up being correct in the long run, but it won't be because of superior hopow generation.