Many of the sounds used in feature films are recorded by professional recordists using professional gear, ie. expensive mics, multiple mic setups, multichannel recorders, and multiple days on location.
I believe that a well-recorded sound is a useful sound, no matter the mic or the medium. So much of the success depends on the context in which the sound is used. If money were no object I'm sure we would all be recording our stuff with the highest-end gear at the highest bit & sample rates. But when it comes down to the real world, most of that super-high detail is converted down to 24bit/48kHz and jammed into an already full soundtrack of music, dialog, foley and sound effects.
Which begs the question: How useful are your "guerrilla" recordings?
Rather than a discussion of the pros and cons of high-end or low-end gear, I'd love to hear success stories of your guerrilla recordings actually making it all the way through to the final mix of your film (or other project).