What’s the deal with Tantalum again? Use them when the circuit calls for additional human suffering?
Yes, but only vintage tantalums are acceptable. That way, the flavor of the pain has had time to age into a distinct vintage.
NP0/C0G are the same thing. NP0 =Negative-Positive Zero Temperature Coefficient (meaning, capacitance does not change with temperature), C0G is simply the EIA three-letter code for an NP0 dielectric:
| ppm/°C | Multiplier | Tolerance in ppm/°C (25-85 °C) |
| C: 0.0 | 0: -1 | G: ±30 |
| B: 0.3 | 1: -10 | H: ±60 |
| L: 0.8 | 2: -100 | J: ±120 |
| A: 0.9 | 3: -1000 | K: ±250 |
| M: 1.0 | 4: +1 | L: ±500 |
| P: 1.5 | 6: +10 | M: ±1000 |
| R: 2.2 | 7: +100 | N: ±2500 |
| S: 3.3 | 8: +1000 | |
| T: 4.7 | | |
| V: 5.6 | | |
| U: 7.5 | | |
C0G's are *quite* good. In fact, if given the choice between a C0G and a Polyester film capacitor, I'm typically choosing a C0G. They're on par with polypropylene film when it comes to distortion (polypro tends to win by a hair), are better for circumstances requiring precision due to their very low temperature coefficient, and fare only a little worse when it comes to dielectric absorption.
Granted...cost per unit might be a factor. Depending on the value, polyester may be cheaper, and you probably won't notice much of a difference in most applications. C0G can be had up to about 220nF as far as I've seen in a leaded package, though they'll be a little larger than polyester in the larger capacitance ranges.
TL

R: There's no reason not to use C0G aside from cost and size. They're fantastic. X7R's are the next commonly available step down in MLCC's and are usable in many positions, but polyester is generally the better choice for everything except decoupling.
Now...how much will this impact your builds? Probably not much. Changing one cap ain't gonna make the difference between god-like toan and poo. Though I'm a fan of using stupid overbuilds in pedals because I'm apparently Mr. Moneybags and like to spend more than I absolutely need to, cause my parents didn't love me enough.