I dont have a netgear router and i'm not using gtk-gnutella but here are my thoughts.
It crashes the router because of the huge amount of connections the program makes. you could try lowering the max halfopen connections and max number of requests from within the program. Also you could try disabling uPNP, gaming mode, vpn and other stuff you never use from the router's config page.
Hmmm - I have seen that theory before - too many connections crashing the router...but it's a very new router, a 108Mbps one, shouldn't that have a high enough spec to handle such a load? Limewire and frostwire work ok.
Routers seem to struggle with lots of connections - I've heard of this before and experienced lockups myself sometimes if gtk-gnutella is left running for days.
If you want an eye opener on how many connections are opened concurrently, fire up etherape. Gtk-gnutella seems to make significantly more connections than frostwire.
Unlikely that the router spec will give enough information on whether it can handle this sort of traffic - guess you'll have to go with a personal recommendation. Probably a case of "you get what you pay for".