specifically regarding 33rpm test pressings; they are rarely much different from the regular pressings....i have maybe a dozen of them and the corresponding regular pressing. a couple are possibly a bit more vivid. in no case are they close to the 45rpm pressing.
so if the choice is to pay a premium for the 33rpm test pressing or the 45rpm......buy the 45rpm every time.
now if you talk about a 33rpm direct-to-disc then that is a different issue. but of course; it would be unlikely to find a 33rpm DTD and a 45rpm of the exact same recording.....i've not seen that.