Good fins last a very long time. I still own the first pair I bought after certifying, a pair of paddle fins that I abandoned for a few years for the same reasons you described. Thankfully, I kept them so that they were still around when I grew disenchanted with the ones I had bought to replace them.
When I first started diving, the kind of fin I had didn't matter too much to me, and when I developed an arthritic knee, I wanted something that was easier to kick. I was pretty much flutter kicking in a straight line the whole time, so ease of kicking was my main concern. It was, in fact, my only concern.
When I finally had knee replacement surgery and suddenly had knees nearly as good as new, my life changed. I started getting into more complex diving, and that meant more complex kicking. I started doing a lot of frog kicking, helicopter turns, and back kicking. Suddenly, I needed very specific fins--stiff paddles. I recently tried some not-so-stiff paddle fins in the pool, and I was shocked by the difference--it took me at least twice the kicks to cross the pool at half the speed of normal while back kicking.
So, if I were you, I would think long and hard about what you see as your future in diving, at least for the next few years. If you see yourself as a straight ahead flutter kicker for the foreseeable future, then go ahead and get a nice, easy kicking fin. Split fins are fine for that.
If you think you are going to do more complex diving, or if you see yourself diving in areas where flutter kicking is going to raise a silt cloud around you, then you want to stick with the stiffer paddles.