IMO: playing to maximize HP is a zero-sum game. So many variables and with the current price-point of $ to HP, it’s an unnecessary constraint unless one is completely budget conscious (false economy if one is doing anything with video) or if one has a predetermined case layout optimized for a concrete and specific functional goal like XYZ raster manipulation, or, more significantly, a precise case size dictated by need to travel and gig on the road.
I have total sympathy for wanting everything to fit neatly in symmetrical rows with full row HP optimization. I’ve been playing that game for several years now. Many times I thought I’d unlocked the Rosetta Stone layout for my fleet of Vessels by mocking them up in modulargrid only to find that the limitations of physical realities meant they could not go where I’d hoped. The shallow depth of them meant that many modules (more of the DIY variety) would not fit at all, and the bulkheads for sync and the fan also meant only certain modules can fit near them. That, and the angled walls on the sides meant certain modules can’t sit flush there. Lars got me over my mental block with the explanation that the Vessels are really 84 HP with bonus room on the sides to aid with temperature control and to leave room for back of house sync connections.
All of that is to say, once I stopped striving for perfect/full HP fits, I had a lot less stress.
So, to answer your specific 24 HP question, if it were my case I’d go with Pendulum, Curtain, and RGB pre encoder for VC. All that said, Fortress packs a hell of a punch in 22 HP but good luck filling a 2 HP gap!
Oh, one other thing. My system really unlocked for me when I moved into triplicate and quads of certain modules. Three of anything has interesting applications for an RGB workflow. A common desire for a lot of folks is to play Pokémon with video modules and catch ‘em all! That’s completely understandable as each module brings unique functions into the mix. But there is wisdom and POWER in multiples of the same module in use. I’m not exaggerating when I say your system could benefit from 2 Passage, a Bridge, and an Arch … IN EVERY ROW!!