Wheel upgrade advice please!!

Ok,

I purchased a cube agree gtc sl about 9 months ago and it came with Cube HP aero wheels made by Citec. I am now considering upgrading wheels. I have been looking at fulcrums or mavics. I have been looking at fulcrum 3's or mavic krysium elites. My first question is would these wheels be an upgrade on what I already have? I know fulcrum zero's and krysium sl's would be an upgrade and if finances allowed I would love either of these. Would I be better off to keep saving and try and get zero's or sl's?

I mainly ride sportives but have started to do a bit of racing this year and I would like to do some more racing. I would prefer clinchers as I don't have any experience of tubs. I what to use wheels for summer months and not just for racing so I am looking for a good all round wheel. I think this would probably mean carbon wheels wouldn't be a runner.

If I decide to buy second hand what should I look out for when buying wheels?
Any other suggestions of upgrades are welcome!!!!

Thanks in advance