The incident I was involved in on a 747 take-off concerned a strongish crosswind up to copilot limits. I was surprised he was not applying any aileron at all. Regarding it as too late to teach someone to suck eggs (at 100kts), we continued. Just after lift off, there was what felt a horrendous wing drop and I can't describe too much more as it all happened so fast. The aileron required was almost full, and we were over the side of the runway. I suspect we were caught by a gust on lift off just as the copilot had still not applied any precautionary correction. The amount of aileron to hold wings level (and the duration) startled me. The reaction of the third pilot was 'what the hell happened there?'
Next time you do a crosswind take-off where the other pilot does not apply aileron, or not enough, during the roll, clock the amount of aileron needed as the main wheels lift off. What was 'saved' during the rotation will be doubly applied after rotation. I can guarantee the aileron will be hard over, at least double or more the planned setting, and the HP will be unaware how much he has had to apply to hold wing level. When you try and explain how much they actually put on, you will be met with disbelief.
Summing up, the point I really want to get over is:
Drag from spoiler uplift is negligible up to climb speed, especially on the roll.
You need to stop that wing lifting on the roll, even at lowish speeds.
Lift off with little or no aileron, into a medium crosswind, and you're in for a surprise.
Once again, the reasons for the United incident are absurd. The wind conditions are no more than 'moderate'. Quite plainly, blaming that for the tailscrape is nonsense. When you have done 35 kt crossswind take-offs in gusty conditions at max weight regularly as part of a very large fleet doing the same, with no tailscrapes, then it shows the reason lies elsewhere!