Speaking about myself: I do only things that make fun, especially in my free time. Haven't found a free gnutella client yet I feel comfortable with. (Perhaps when Mutella becomes better documented, Max *g*, or Xolox goes OpenSource)

PS: Veniamin, currently I prefer sending a hash always when the other side requests it (0.7 proposal appendix B). Small files are not that common in Gnutella these days, so it's not a big traffic issue IMHO, also hashs help finding alternative locations when a host is "firewalled" or drops connection.