It depends on the beer and the sugar, some of them are considerably darker and can give more "raw" sugar character. However, at .5 lbs I doubt you probably won't get much character from any of them especially in a bigger/darker beer. Ethnic markets are often a great place to go for interesting sugars.
I've never seen Barbados sugar, but I've used Demerara in England, and Turbinado in America. I'm dammed if I could tell the difference between them.
At 1/2 lb in a 5g batch, I don't think you will get any off flavors.
There are only 10 types of people in this world. Those that understand binary, and those that don't.
Sorry to bump this again but I have one more question. Its getting close to bottling time for the English mild I brewed. I did find Demerara sugar at the local grocer so I was able to use it in my batch.
My last question is can I use this for priming and if I do will it contribute to more molasses-like flavours? Or do I run the risk of ending up with some off, wine like flavours and should just stick to dextrose?