kk: I've loaded the 165 gr. Golden Saber quite a bit, but not with 4756. Until recently, I hadn't been firing .40 a lot. That changed a few months back with the purchase of a CZ 75 B. It is the most accurate .40 I have ever seen, maybe the most accurate pistol I have seen period and that goes back nearly 30 years. I looked at using 4756 and WSF, along with some other powders I have, but I try to load for minimum muzzle flash and the guys that I know that use it, told me to expect flash. I like the powder a lot for cast loads in magnum revolvers and I never got around to using it 9mm, but the people I know that have are very impressed with accuracy.
I'm not helping you here, but something that might is a phone call to the Techs at Sierra: 800 223-8799 They make a 165 gr. JHP, and since you're not likely to find pressure tested data for the 165 gr. GS, anyway, this will work. Golden Sabers with their very short shank/driving band, usually run at the lowest pressure at a given weight. I've loaded tens of thousands of them in 9mm, .40 and the .45 ACP. Sierra JHP bullets have a truncated cone shape and usually the longest bullet shank by weight and caliber. Typically, their bullets with the same powder charge as another brand of identical weight bullets are the highest in pressure. I bet they have the data for 4756 and will give it to you for start charge and max. load with velocity for the max. charge. BTW, I use Ramshot True Blue and Silhouette for this and if you had them, I could give you data for the GS.
As far as 9mm goes, I have data but it is from an older manual and the max charge runs a bit higher. If you don't want to load +P, I'd say keep it at 6.0 grs. with the 115 gr. bullet. With a charge any higher you probably will get into +P pressure.
I don't use Power Pistol. Tried it once and that was enough for me. Very bright flash in 9mm and .40 S&W, but I can help with some load data. For the 115 gr. 9mm 6.7 grs. is a max charge for an FMJ at 1.120" OACL. Velocity is 1280 FPS @ 33,500 PSI. Start at 6.0. If you use a JHP, load to the same OACL and you'll be fine. For the .40 165 gr. GS, check with Sierra on that one as well. I don't have data for it.