I don't know much about compression but I can say I do know a bit about hardware, and honestly, having gone from using HDDs to repack versus a dedicated array of SSDs, I'd honestly recommend repacking on SSDs. Now this example is anecdotal and my own personal experience but I still think it has some value to the discussion.
Most modern cell arrays can endure a fairly insane amount of write operations especially for the price, now for obvious reasons I won't say the models I bought but most 1TB drives can easily endure at least 1PB of write operations to the overall NAND array, for those of you who don't know, modern storage controllers are very efficient at distributing the wear evenly amongst the cells of an array, and are a far cry from the SSDs of yore.
Now in terms of my own experiences, to date I have written over 150TB across my repacking-specific drives, and I'm yet to see any degradation in performance for read/write operations. Now compared to my old setup of HDDs, ranging from 2TB to 4TB (all new, from reputable brands), I noticed pretty significant drop offs in performance for write operations and seek times after only around a year of use. And yes before anyone asks I did de-fragment the drives regularly. Finally, in terms of cost a 1TB drive, at least in the US according to PCPartPicker, a half decent 1TB SSD goes for comfortably under US$100, like the
MX500 which is only going for a slick $70.
Especially for repacks with a large amount of loose files I'd recommend repacking on SSDs over HDDs any day of the week.