The host count is very likely to go down a little because LimeWire ultrapeers devote less bandwidth to forwarding pong messages (and those messages are used to compute the host count). This has nothing to do with your actual search horizon and if you ask me, the number does more damage than it does good.

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Morgens ess ich Cornflakes und abends ess ich Brot
Und wenn ich lang genug gelebt hab, dann sterb ich und bin tot

--Fischmob