You should be fine with the switch so far as nutrition goes, but there is a faint risk that he won't eat the new stuff, especially at first, so drastically underfeed the first feeding until you see him eating.

If he doesn't eat it when you first try, fast him a couple days then try again. Don't keep trying every day or the uneaten food could foul the water. I personally wouldn't do an extra gravel cleaning just because of it, but scheduling day one right before a scheduled gravel cleaning would be a good idea.

Some bettas really do refuse to switch food. I've never heard of it happening from one brand to another, but I have heard of bettas who once they were fed live or frozen for a while wouldn't touch anything dried.

 

If you want to try every day you can - you just need to remove the uneaten food. Drop one pellet in, if he eats it offer another. If he doesn't remove it right away.