You probably know this but it's good to run a cluster with an odd number of nodes. You don't even need another full node, just a quorum node like a RPi.
Yes, of course.. I'm actually in the process of replacing nodes. The original 3x Ryzen5 4-core 32Gb hosts are being replaced by Ryzen9 12-core 96Gb hosts.. its just taking a bit of time. As long as I only ever take one down for updates at a time, its no bother for a home-lab environment.