Turbinado, Belgian Candy or Corn Sugar?

I am formulating a IIPA recipe and need some guidance. I am curious how much of any of these to use to augment my grain bill?

What percentage of the grist fermentables should be from these sugars? What risks do I run if the percentage is too high?

How to decide which to use?

Should I stay away from adjuncts and do it all with grain alone?

Thanks in advance for your comments, suggestions and advice.

Rick

Keep in mind that the more sugar you add, the less body you'll have in the final beer. It would taste pretty watery if it's a lot of sugar. I wouldn't go with more than a few pounds at most.

There's nothing wrong with adding sugar to an IPA, I use 1.5lbs of corn sugar in my IIPA, but I would try to make most of your batch with grain. If you're thinking about doing this because of mash tun size, then I'd suggest using a late addition of extract instead of a bunch of sugars.

For something like an IPA, I'd keep sugar under 10%, and maybe stick closer to 5-7%. You will possibly get a bit more flavor and complexity from the turbinado than the others. Radical Brewing has a good discussion of using sugar.

Edit: I think some sugar in a IIPA is a good idea--it can be nice to lighten the body so it's not too syrupy.