I've been moving away from it. I prefer the higher GI and lower fiber content in white rice flour and tapioca starch. Plus, buckwheat just doesn't taste that good. If you use sorghum flour, corn flour, brown rice flour or cocoa powder though, I would recommend adding a tablespoon of buckwheat to the preferment. Buckwheat contains very high levels of phytase, the enzyme that breaks down phytic acid. Simply soaking or fermenting sorghum or cocoa won't do much to remove the high levels of phytate, but adding a little buckwheat to the preferment is a great way to remove the phytic acid without adding gluten (most people use rye flour for its high phytase content but rye contains gluten). I will say this - a little buckwheat and/or sorghum goes well in the banana bread because generally banana breads are darker and it lends a good flavor. However, for pies and cornbread, keep it away.
Don't put your trust in anyone on this forum, including me. You are the key to your own success.