Since you asked for an opinion. I have recapped consoles over many years with FC's.
Taking into account 'space constraints'. They sound ok in my opinion.
It is a subjective opinion.
I did some work for a place that was grossing over a MILLION dollars a year replacing caps and opamps in other manufacturers equipment. I've also been around and around the capacitor merry-go-round with many, many engineers at multiple major international manufacturers.
Here's what I know:
However, the way the electrodes are formed may have some effect on other parameters
Physical construction of caps is critical. Rigid dielectrics want to 'sing' when subjected to vibration. X7R (and similar ceramic dielectrics) are particularly well known for this. COG is way better for the lowest cost ceramic caps, where performance is still a concern. I'll not throw my hat in the ring endorsing a particular Aluminum cap. None are particularly 'great' IMO but there's usually plenty of reasonably priced options that can do the job...if you need a _bunch_ of µFs.
The single biggest problem with liquid electrolyte types is they leak. The physical dimensions make them such that often a significant torque is applied to the leads as the cap wiggles back and forth with vibration. Industrial PCB manufacturers usually goop some RTV or similar to hold the top of the cap fixed. This can add many years to their lifespan. DO NOT let that electrolyte leak onto your PCB copper. Depending on the chemistry, many (most?) will etch the traces right off the PCB. I've seen them eat right through multilayer boards. Beefy ground plane and all.
You can always spend a fortune on esoteric audiophile grade caps.
In the audio path, the WIMAs seemed to end up in a lot of boxes over the years. Particularly the boxes that seemed like they maybe didn't pinch too many pennies. Film caps generally perform better that 'lytics if you can both afford them and fit them in the box. "Polyrazzmatazz" (as one colleague called it) cost extra, and depending on the quality level of the rest of the system, may not be warranted.
EDIT: BTW, film caps tend to fail gracefully, 'self-healing' and just losing a bit of capacitance. They last, effectively, forever compared to the Aluminum lytics.
This applies to 'polymer' electrolytics and also to Tantalums which I would never use in a high quality audio setting.
My old boss, who taught me a _lot_ about audio, used to swear by solid Tantalums in the audio path. He used 'large' (0.47-10µF) 16V ones for AC coupling filter stages together. He's the only one I ever knew that preferred them, but he was pretty sharp, and he knew his stuff. IDK, never having tried them because:
The cell phone folks prefer Tantalum caps for size and weight. When cell phones took off late '90s, you basically couldn't get them if you weren't SONY or Motorola. This actually led to an (AFAIK) ongoing humanitarian crisis. For details see:
https://en.wikipedia.org/wiki/Tantalum#Status_as_a_conflict_resource
I'd rather not fuel that particular fire. The problem is cell phones are rather handy...
cut the sound in and out and made a lot of noises, it was not nice.
At one place I worked we used to say: "There's three kinds of audio. Works, doesn't work, and sounds funny. And sounds funny is pretty close to doesn't work."
Their idea of sounds funny could be rather particular too, but as you might guess, cost _was_ a huge factor in cap selection there.
BTW: Good microphones and speakers, with proper gain structure and, naturally, a good _source_ usually goes a lot farther that all the schmantzy opamps and caps combined. You can mix the best musicians on the cheapest gear out there, and get them to sound good, if you know what you're doing. But if the kid can't sing in key, or the drummer can't count to four, all the 990s in the world aren't really going to help much.
