SR assault definitely should be used over Adramelech bow.
SR assault usually should be used over Illuyanka gun (unless you need the HP from a glorified, more expensive-to-level SR defender).

First, would you agree that Adramelech Bow/Illuyanka gun have zero or near-zero odds of being in a 'late game' weapon grid?
If so, then you know that whatever resources expended to level it will only be for temporary gains.
Would you then agree that when leveling place holder weapons, efficiency (ratio of resources spentower gain) would be a priority?
If so, then consider that SRs take roughly half of the resources needed to skill lvl, compared to SSRs. And a SR assault would provide known and predictable gains (Rush/Barrage.... aren't those things). As for the Illuyanka gun, it's a matter of the general preference for assault over defender, unless you really, really need that HP.