I do a lot of shooting at night with spot lights. I usually use illuminated reticle scopes and have found them to work pretty well. But I keep hearing how 8x57 fixed power scopes from makes such as Kahles or S&B are the best for this type of shooting. Anyone here have any hands on experience with these scopes at night?

56 / 8 = 7mm exit pupil. That's the max a young pupil can expand to let light in. If your pupils do not dilate to 7mm then the extra light and size is wasted. When at the eye Dr. ask them to check the measurements.
Years ago when Weaver made their steel scopes in Texas, I had an 8x56mm and loved it. it was solid, tracked well, never needed rezeroing. It was on a Sako AV 7mm RM. It did not have the illuminated features. Slowly their glass quality diminished when compared to newer improved glass . At the time S&B, Kahles and Zeiss were the major players. 1980's-1990's. Zeiss was the best glass, still with no illumination.
Currently the high number variables are the rage, which caused optic companies to drop their 8x56mm line, at least to the U.S.. In Europe where boar night hunting is acceptable and the norm. The 8x56mm is more widely available. Other companies made them but not in par with the alpha glass. You need all the quality you can get.
I personally have not seen an 8x56mm illuminated in the U.S. it doesn't mean they are not made.

Currently if you can find a newer production scope from the following list, jump on it. Swarovski, Zeiss. S&B. Off memory, I don't think US Optics. Night Force, Optolyth made them.
Night hunting is becoming more available in southern U.S., TX., GA. etc.. Most are using dedicated night vision scopes. That is your best bet by far if allowed in your locale. The best will cost you close to $5k US
If not, get a high end scope with the adjustable illuminated reticle and variable range that will suit your type of hunting. Best of luck to you.

The best 8x56 that I have used has been a current-production Schmidt Bender Klassik with A4 reticle, which has no illumination but is heavy enough that you won't lose it in poor lighting.

Thanks for the comments guys. I appreciate your thoughts on this. And apologies - I obviously have Euro cartridges on the brain, as I certainly meant 8x56 scopes.

Mauser Stutzen 8 x 57 with Khales 8 x 56, reticle 1 without ilummination: Excelent in the dark, in use for 25 years with many jabalies in your history. In Argentina it's legal hunt in the nght. Regards, Hector

Don't forget the design originates in Northern Europe where there's usually some snow during hunting season. Snow + moon + dark target (boar) = good shooting. The reflection of the moon light off of the snow is a key ingredient.

Don't get me wrong. I'm a believer, but it's important to understand why the 8x56 + #1 reticle became popular.