wheel set comparison and upgrade or no?

I bought a cannondale hi-mod black inc road bike synapse for training and racing in triathlons. I was able to get it used and it could have come with ENVE wheel set that i was told was around $2600 wheel set retail or get the bike for quite a bit cheaper if I did a lower level set of wheels. I did the latter and currently have Maddux disc 2.0 wheels on my bike. I'm new to biking so not sure what level of wheels are that i currently have or how much improvement I would get with either (1) going back and seeing if I could still get a deal on the "used" ENVE wheelset (2) get a different wheel set such as Zipps 404 or 808 or 303 ? (3) none of the above and not get a new wheel set. With the thinking that I may only get 2-3% improvement by new wheels.

Most people have told me that I am not going to see much improvement by new wheels or race specific wheels and others have told me that you see a significant difference in ride and speed with a better wheel set But of course the question becomes at what cost?