I read about this topic 100 times before putting a blanket on my car.

I will give you my first hand experience.

727 with multiple converter's that stalled in the 2200-3000 range on motor. This would equate to around 5000 or so on the trans brake with boost.

Now driving around, you're not into boost very often, so it's a fairly tight unit for regular driving.

I had a deep steel 727 pan on it, with an RCI blanket (fairly short, only covering the main case area.

I started with a nice size 14 x 14 tube/fin cooler mounted in front of the radiator. Long hauls, or making rounds would get the trans REALLY hot. Added a second trans cooler under the car (8 x 12") which marginally improved it, but still did not solve the issue.

We're talking 300 degree's hot... enough to melt the front pump seal in round robin bracket racing, and spew fluid everywhere.

At the same time I went to an aluminum B & M pan and a CSI carbon shield. Since then the temp has NEVER gotten over 200 degree's in any situation.

I can't say for sure that it was the blanket or pan alone that solved it, but I can tell you FOR SURE one of those two was causing me a HUGE issue. Since I had used that pan on cars before with looser converters and not had this issue, I tend to really blame the blanket for causing the heat problems.

Can't say why some guys get away with it, and not have any problems. But I can say that the blanket did give me issues...