This is something fairly new, as it is something I've not only played with the idea of- but actually just experimented a bit.
Since I've been trying around SS, I thought it was an awful choice given at how the lack of Guard made it really unstable to go about in Arena...but it looks like I'm sort of catching on. It requires some strategy, but it might be possible.
As to the actual concept, it's based on not only raising his Spd to "doesn't get doubled by literally everything" to actually doubling some of the lower- and even some in the lower 30s (given appropriate support). A lot of the dudes that run Bold Fighter are the main threat, as well as some of the middling Spd Nowis and onward. Being able to counter Bold Fighter is really good, and I realise he's no longer solely Enemy Phase on some context.
Lastly, I'm aware it's a given that other characters would run this concept better. Namely, Robin (and maybe Boey, to some extent). Henry's arguably big advantage is his amazing raw bulk in HP, Def and Res, however.