I'm on a low carb plan right now but I'm thinking of switching to low fat because I miss the foods I can't have while doing a low carb plan. I'm
thinking of re-joining weight watchers and slowly re-adding the carbs
back in.

Has anyone here gone from low carb to low fat sucessfully? meaning
little to no weight gain during the transiton?

I never transitioned from one diet to another. I stopped to gain some weight first

But seriously. Do you have an account at fitday.com? It's free.
You could put your food in from your last on plan day and see how it rounds out. Over the next couple of days just start tweaking for a few more carbs and a little less fat.