I always love how the Eridani "Light" Horse end up with assault mechs for their commanders and now the upcoming Kickstarter with the Sagittarie..
As for the unit, I can see the 8R as a good choice for close range battles in locations like crowded city. Maps with lots of buildings, base defense, heavy forests, jungle and the like. IS pulse lasers suffer from range issues in more open field combat unless they're mounted on faster moving units like the Anvil or the Nightsky. The C3 command variant is an excellent command lance and air defense unit, and fits in with Davion C3 doctrine of the time. As for the rest, I'm not super impressed by the attempts to increase survivability while focusing on VSPLs or Reengineered lasers as your main offensive battery. The fact that none of the variants mount X-Pulse or Large VSPls is a bit suspect in my opinion, but I get the demands of the time.
A Dark Age mixed tech variant of the baze 8R Sagittaire that does a 1 for 1 IS to Clan swap on the weapons makeup would be horrifying. It would easily balance out with the RecGuide refits of the Black Knight, Marauder II, Marauder, the Lancelot, and the Flashman.