We did this on Saturday. It was crappy (cold and rainy). So we played much faster and saw some new shots. I would recommend it in any weather.
I am currently a 7.6, course 9. Our blues are 72.9/138/~6600, and our reds are 66.5/121/~5300. There were some holes that were way shorter, and some others that were blocked by angles from the up tees.
I am in a distance slump, so it was great to take the pressure off the driver and try to score. I shot a 76 that could have been a couple lower but that is always the case. I posted it (75 ESC) and it was a 7.9 differential. I have an 82 from the blues that is a 7.5 differential.
I think your most likely score is your course handicap (based on slope only) added to the rating. I was an 8 from the reds and that would be a 74.5, so it was pretty close.
Everyone should do it. It gives you some different angles and distances, and it should be a faster round.