I put mine orbiting my "anchor" ship at 2500 and 4000 with afterburners on. In PVE you have to jump through gates and whatnot so while my anchor (usually a BS) slowboats or prop mods it to the gate my logi's just high speed orbit him. I never had a problem if my logi's got aggro (I used Basi's and Guardians depending on the group tank). Throw another rep on whatever needs it and keep killing. I assume you're using T1 logi? Can you not tank/speed tank them up enough, or are the smaller reps not able to keep up?

If you mean in PVP then everything is variable. I'd still normally keep them in tight for easier multitasking.