If I had another ten points available, that'd be the investment I'd make as well.
Well, as far as ChapTacts goes, they do provide minor boons to different roles:
*Ultramarines is very situational and depends on how well triggering one of the doctrines would improve the rest of your army that said turn.
*White Scars gives Hit&Run, which speaks for a
CCW+
BP squad. If you charge a unit that has been blinded by a Cerberus launcher, you're hitting on 3+ and will be hit on 5+ for 2 rounds of combat, which means even 5 scouts should be able to survive charging a standard unit for 2 rounds of combat and then H&R out for another charge in their own turn.
*Imperial Fists speaks for using the
LSS as a gunboat with the scouts wielding bolters to maximize ranged damage output.
*Iron Hands are fit for a small objective camper unit, with camo cloaks perhaps.
*Salamanders would only provide a boon to the combi-flamer, and so are negligible.
*Raven Guard gives scout and first turn stealth. For a unit embarked on an
LSS, this is worthless.
I'd say White Scars and Imperial Fists are the only tactics that would make me lean towards one build over another merely because of the tactic itself.