According to your site, you seem very adamant about people not redistributing the unmodified icon bundle. However, as the right to redistribute unmodified as long as attribution is maintained is one of the core freedoms granted by all successful free/open licenses (Creative Commons, GPL, BSD/MIT, etc), I've had to file LED under "Pseudo-libre (Redist limitations)" in my resources collection rather than "BSD/MIT/Attribution".

Furthermore, it introduces uncertainty as to whether LED icons are compatible with strict copyleft licenses like the GNU GPL and the ShareAlike variants of Creative Commons licenses.

Unfortunately, in my experience, enshrining this kind of requirement in licenses to increase popularity tends to be counter-productive as it feels heavy-handed and acts as a deterrent to a portion of the honest user base while the dishonest users just ignore the redistribution requirement, assuming they'll never get caught or ignoring anyone who isn't a lawyered-up multinational.

I ask that you clarify whether this redistribution restriction is a licensing condition or simply a very strong request.

My advice would be the latter, coupled with the use of a CC-BY (Creative Commons Attribution 3.0 Generic) license since that would give a good first impression, be more clear to people like me who look first for the license and second at the comprehensiveness of the icon set.

Most importantly, the CC-BY metadata would make LED appear to people taking advantage of Google and Yahoo's "search by license terms" functionality... significantly increasing your exposure to new users. (Though I don't have data handy to back it up, in my experience, you gain far more new users to CC-BY than you lose by allowing redistribution. Heavy-handedness tends to get peoples' backs up.)