The FT-2 caps are seriously decent. However, they are (as above) seriously large as well. I used them in my spare phono stage for a while but that needed four of them and I ended up putting it in a larger case, which was still a bit of a squeeze. Interestingly in view of the topic, I actually changed them for Audio Note, as these gave a slightly 'bigger' sound.
It's all tinkering at the margins though, and relatively very small changes. If someone says 'night and day' in relation to swapping capacitors, then either the original ones were broken or there is the requirement to justify an unjustifiable expenditure.
In about five decades of messing around with electronics on and off, I can only remember one time there was a night and day effect for a capacitor. That was when, as a wet behind the ears youth, I put a screwdriver in the wrong place when messing about with some EHT stuff. 'The wrong place' was across the terminals of a big electrolytic smoothing capacitor on a very high voltage line and the end result was definitely 'night and day', as it all went very dark and very quiet. Dark, because I'd blown a chain of fuses, including the incoming street mains, and quiet, because I went deaf for a few days. That taught me a few lessons. One of which is that the mess caused by an exploding capacitor is something best avoided. The second of which was that when playing around with anything over a few millivolts, if there is enough current then things can go very bad, very fast.
