There are other syrup type sweeteners that will work, but all will modify taste/texture to some degree.
Lyle's golden syrup (made from beets, but really close to corn syrup)
agave syrup (not as thick or sweet)
malt extract (not as bitter as molassas, but with similar qualities)
rice syrup ( great texture and nice light flavor)
honey (remember that honey is 2.5 times sweeter than sugar
Also Acacia honey is white and very mild or really raw brand is amazing texture and not too strong)
simple syrup (1:1 ratio of boiled water and sugar)
maple syrup (I use lite AA when I don't want that maple flavor)
These are my sticky suggestions, but a liitle home brew beer science is kicking in, I assume for BBQ sauce....besides being cheap and easy to procure; Corn Syrup is what we call an invery sugar, It doesn't react as quickly to fermentation or heat. so It may keep the burn factor down a little.
Then the molassas show.....
the biggest deifference will be between sulfered or un sulfered. sulfered molassas is sweeter, it will last longer, and it has a nice sour finish that is kinda nice.
there are plenty of High Molassas sugars to choose from that are way fun to experiment with.
The most mild is Sucanat it is raw sugar cane juice that is evaporated and paddled until dry.
then you have Turbonado the same as Sucanat but heat is used, it has a deeper roasty flavor, If you live in the south sometimes you can find folks who fire the sugar houise with wood or sugar cane. a little smoke flavor comes in.
finally my favorite Damiera
It is sucanat that has extra molassas added during the drying process. it has the texture of hard candy that has gone soft with an intence coffee like flavor.
Some of these may be a challenge to find. I work at a Whole Foods, but bakery supply shops, or home brew shops should have some of them.
keep the bbq lit