Seek the Beast is an Instant with "Until your next end step", so unless you're main-phasing it to hit a land drop you'd otherwise miss it's a straight upgrade.
You have three turns to play the cards from Reckless Impulse. Two of your own turns and one enemy turn where you can cast instants.
You have two turns to play the cards from Seek the Beast. One enemy turn where you can cash instants and one of your own turns.