Actually, the Hermod might well be the better move. The Metropolis is based on the RYK-185 sequencer, which was originally designed for the Roland System-100m way back in the early 1980s. The idea behind it was primarily to allow sequencing that included ratcheting behavior, ala TD's late 1970s work, and while Intellijel did a lot of updating, it still has its roots in that older device. The Hermod, though, is an offshoot of the much more complicated Pyramid, Squarp's standalone sequencer, which was more of a 'ground-up' creation. It also helps that the Hermod can provide MIDI support, plus USB hosting, which would allow you to connect something like an Arturia Keystep directly to provide keyboard control (and an extra sequencer, too).
Still, consider that Bubblesound 8 hp quad VCA/mixer...it gives you back 4 hp, and would open that last space on the bottom tier to 8 hp, allowing that second Function to go in. And once the ONE goes back up top, you'd still have 2 hp, which is plenty for a little 4-in submixer after your source modules and before the VCF if you want to sum-down a couple of sources to a single signal. Overall, this is looking way-snazzier!