The biggest advantage I see of the rasail is that we can use the lietnant order with him. As far as I can remember you can't use lt orders for a triad it only counts for the lt so yeah you get an additional order with the rasail lt that you should use, normaly you got CoC so you can sacrifice the rasail
Not only that: - Great resilence with 3 +1 wounds (+ optional Symbiomate (+ optional healing from Symbiobomb)). You can make several mistakes/sacrifices and keep going on and on. - Up to Burst 6 with Rasail Spitfire + Chaksa Pistol. You can get some non-oposed rolls thanks to that. - Sacrificial Heavy Flamethrower to push forward against skirmishers or to defend itself (even better defense with Minelayer). - Freedom of movement thanks to Nanoscreen.