Yes, sweet potatoes are better for them than white, I give them (cooked and mashed up) to Timber every day. He's picky too, and that's one of the few vegetables he'll actually eat regularly. I understand the picky bird pain, Timber isn't a good eater at the best of times and I've tried everything. He's actually gotten better in the last few years. He ate (yes, actually ate) a piece of raw carrot the other day. That's after years of refusing to even try them. He would still starve rather than eat a pellet. He's also fond of eggs, either boiled or scrambled.