1. Symbolic Links get you different options, rather then faster/smoother play. However, if you're going with IS Boxer, it will virtualize your configuration anyway... which is the only real advantage of symbolic links.

2. Your toons can, as a 5-man, gear closer to the highest raid content then ever before. With straight badges you can get Tier 9.1 gear, which is very nice. You can also get very good pvp gear, either through arena, battlegrounds or using heroic badges to purchase it. There's a ton of content for 5-man, and if you want you can try 10-man content or to partner with another boxer. Also, you could easily 1-box raid if you so desired.

3. IS Boxer is safe for warcraft. It doesn't let you do anything which could get your account into trouble. I've heard of someone being banned in Lord of the Rings, but that was more having a toon crafting (AFK) and not able to respond to a GM, not so much the software being used. There are hundreds of players using IS Boxer for warcraft and I've yet to hear of a single player banned.