Agree with pp's. I have only started using fins in the last 12 months and largely think they are the most unnecessary swim "toy" you need. The paddling with teaspoon sensation you descibe is the main reason I don't think they are a very helpful tool.

I know people who have cut off some of the fin to reduce their speed when finning (but I could never do this to my shinny fins).

I think that as long as you keep their use to a minimum during a session (ie. less than 10 - 15%) it may help becoming to dependent on them. Also, if you want to fin, do that part of your workout just before a rest so that you don't swim barefoot and feel soooo slow straight after. Another mental tool I use to limit using them too much is to weight any laps you do with fins lower than a normal lap (ie. say to yourself that in your logbook every fin lap only counts as half a lap - or whatever works for you).

I agree with Wahine though that they are great for helping you to feel what fast, efficient swimminng feels like - I would simply say that each time you slip on your fins make sure you have a reason for it - such as doing a catchup drill or something you are stuggling a bit with when not wearing fins. Also try not to be lazy when kicking, keep your kick as similar to normal and make sure you are doing each lap faster than normal swimming to stop you from cruising too much in your fins.