Hi, Slidecage, I hope you’re having a good day.
If you like to gamble, it’s a 50/50 as to whether you can single pull your way to the Big Prize (2HE4, in this case) for less than 6K HP. There’s a 10% chance you’ll pay 6K anyway. But a 40% you’ll bust and have to spend more to get him to drop.
The people I see discussing buying these regularly just pay the 6K.
If you hit enough of these, over time, it would regress to the mean, and your average spend would be … around 6K.
Maxchamp a 246 before adding levels to a 270 … personal preference? doesn’t matter? Those last 20 levels (40 covers) are worth 22K iso, 350HP, 23CP, 2LT, and a mighty. You can claim those now or later, or skip it, if you’d rather put those 40 covers toward richer rewards.
If you do finish it, get it to 266, it won’t show up as a chara you can add covers to, which irritates me, so there’s a very narrow reason to not finish it first 
Haven’t seen a 2Storm4 offered lately in a vault. There was once recently for $25.
Yes, if you can buy a 270, you could merge it with your 370 and get right to 450. Or spend 3 covers on it, get the first LT, then merge it, and be at 451 and one LT richer.