"I am debating between “dual platform/SPD” vs “two sided SPD/SPD”. Once you have SPD, would you ever use normal shoes? For the dual ones, is flipping to the correct side a big annoyance?"

Dual sided are great and inexpensive. I love mine. Picked up Shimano mtb shoes for $50.

Easy to learn how to clip in and out. If you are near a border why not hop over to the USA and buy.