I don't know... I have Dashing at lvl 5 but I
have noticed I serious decline in SP consumption compared to lvl 1 Dashing. But I would go for a horse when going through the field
I know that earlier in this topic it was said that a the 'Own a Horse' Bliss Reward was rather useless, I have found it quite handy to have my own horse. A horse you rent will run away soon after you dismount, while your own horse will not. Yes, it might run away when a monster attacks it, but it is similar to keeping your Bounties safe. Just put your horse in a corner where monsters normally don't roam and go kill monsters/gather materials. Pick up your horse when you want to travel further.
A horse also makes it way easier and faster to transport Bounties, since monster cannot attack your Bounties while on your horse and you cannot Dash while carrying Bounties.
Plus, she is just too cute <3 My black mare Cinder takes me and my dog Chale everywhere!
Still haven't been able to continue the main story XD University takes too much of my time >_<