Would actually like to try that. I would have to be blindfolded, tied up, and gagged so I would actually be forced to endure it though, at least the first few times.
It's definitely disappointing. I mean really, if they don't want to swallow then they're not really giving it their all to get you to cum. If they swallow then chances are they like it and they anticipate it and will work that much harder to get you there.