All in all, I've been playing for about 20 years (+/-), however, I've only been playing seriously for about a year. Most of what I've learned about harmonicas themselves has been from the ones I've owned. The only exceptions are the chromatic and the octave.
I have a chromatic, but it's not a typical one, so it's a little awkward to play, and most songs don't fit on it well. The octave, I haven't actually played, but I found out about it when I was researching one of the cheap harps I have. I found out that what have is a tremolo (a cheap chinese tremolo that cost only $1.99), but I also found out about the octave harps, because they are constructed in a very similar manner. The only difference is that the tremolo has 2 rows of reeds that are tuned to the same notes, but the octave has 2 rows of reeds tuned one octave apart.
As far as the tabbing goes, well, at first I had no intention of posting any, but then I decided A) I could probably do as good a job of tabbing as most anyone else here, and
if I'm going to use a site so heavily, I might as well contribute. Since I'm not excatly capable of doing so financially, I decided I'd help with content. I've slowed down substantially on my posting of tabs, but there are a few reasons for that including but not limited to running out of tunes I remember, and I'm trying to catch up with recording mp3's for the tabs I've already written.
Part of what drove me to post so much was the desire to reach "Heavy Contributor" status. I'm still gunning for the #3 spot, but that's not quite as important, and it'll be a while. I could just post a mass of tabs, but they wouldn't be quality tabs, and while I don't mind being prolific in my postings, I'd rather post things with meaning (at least to me).