You don't use an oven to rework SMT, depending on the part in question you use a hot air station or just a soldering iron.
There is also no reason for an electret to be worse than an externally polarized capsule; a bad capsule is a bad capsule, irrespective of polarization.
In fact, I would make the argument that a mass-produced electret is likely to be most consistent than an externally polarizated capsule build to sloppy tolerances. The good electret manufacturers make millions of capsules a year so they are pretty good at it . . .
Yes, that is true. Quality of the capsule is all that matters.
The Behringer C2 (and the Audio Technica AT2020) use a "transsound TSB-140a" electret capsule. It is OK, but not great. Certainly of less quality than the Behringer B5, Studio Projects C4, which use a (better) permanently polarized element.
Note that the construction techniques of capsules can be either standalone capsules, or they can be built into the housing. That is, the diaphragm is glued to a ring, and the back element (charged or not) is put behind it and the whole lot is inserted into the mic housing. Examples of electrets built this way are TSB-120 (transsound) and AT853.
Richard