Isboxer would've been later in TBC / WoTLK, iirc. TBC was done primarily with hardware boxing and then Keyclone and Isboxer.

As long as you're atleast hardware broadcasting then you'll be fine doing dungeons, although depending on your group comp you may be limited in what dungeons you'll be able to successfully do, heroics especially. Prot Paladin + 4 Elemental Shamans is a very solid and safe group, especially leveling 60-70 in dungeons. 5x Elemental Shamans is arguably the best for clearing heroics though.