Shurries is definitely a good idea now that you mention it. That huge burst of speed could probably give some nice AD boost, but it also adds some great regens and some decent survivability.
Sejuani really doesn't do that much damage, though. She can do AoE damage and Hecarim can do AoE damage, and both can initiate well and both can jungle, sure. But Sejuani is way more utility-focused and Hecarim seems to be a lot more damage-focused.
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~Peaf~
"Later that day, I f***ed a panda." - PSO