I went last year and had a blast. It was definitely a change of pace from typical outdoors wars.
A lot of people who attended last year didn't have modded blasters. The ones who did mostly had the most basic mods - AR removals, CPVC barrels, etc. It didn't put them at a disadvantage most of the time unless they were in the atrium or the mezzanine (and even then, there's plenty of cover).
You could use a +bow, I suppose, but honestly I think it would be pretty unwieldly. A lot of the action happened in tight corridors, narrow hallways and stairwells. Being able to maneuver and having a high rate of fire will probably be more important than range alone.
As for restrictions, I think they do it on a case-by-case basis.
+bows and similar have been used to great effect in prior Dart of Wars. Yes, there's plenty of tight corners that lead to intense shootouts, but there are also several long corridors and a wide-open atrium perfect for taking potshots at range.