Spoiler drag on roll is negligible. The darn things don't have much effect below 250kts even, below 140 kts hardly any effect at all
Friend of mine was F/O during a take off in a 737-400 with 25 knot crosswind from the right. The captain pre-set almost full wheel travel right from brakes release. This was his personal choice not a company requirement. The aircraft was runway length limited on this take off. As the story was told to me by the F/O a few days later, around 120 knots the acceleration slowed markedly and at VR the aircraft was extremely close to the threshold.
He described the decelleration as like a car going through a deep puddle and momentarily slowing except this was a 737 that kept going and the V1 was clearly invalid under these circumstances. During simulator training we demonstrate the effects of spoiler extension without reverse actuation or RTO braking during a high speed rejected take off. In the simulator at least there is a definate sense of immediate decelleration and after initial engine spool down the decelleration green arrow is seen on the PFD. As the speed slows below 80-90 knots the green arrow shortens. This suggests that the spoilers when extended at high speed during take off do definately add significant drag for a short period.
This further suggests that excessive control wheel deflection to counter a crosswind in the 737 during the take off run could invalidate V1.