If still godd after 5 min, then filter is probably OK. People have worked up to about 1, miles on 23cm, but not FM, and only under exceptional conditions. So would a Yaesu FTR monoband mobile. Comet and Shimizu make a small yagi and quad, respectively, that is designed to be used handheld. The repeater was transmitting 30 watts. I know a few of the people who are repeater owners, and they have worked hard to build and maintain their equipment.
Icom repeaters use the Japanese bandplan of 20MHz separation. See the appropriate Wiki page for further information. You can get away with a short run of or LMR on 70cm. Most ham stores don't bother to stock it, though. It's very good to see Icom America taking another stab at popularizing the 23cm band in the U.