I do like the idea of a unit of 15 silver helms instead of the seaguard. They keep up with the phoenix's nicely (M9 heavy cav is pretty sweet), provide extra attacks to thin out large units, lets the champ take a challenge if they enemy throws out a challenge, the 2+ armor combo's with the frost's -1 to
str aura really well, and provides 2-3 ranks to help break steadfast. Plus the biggest reason is then you can be 100% themed, since you won't have to call on Lothern to provide troops to your army