Well I suppose part of the question lies in how much the heaver springs are going to cost and whether you should get 2 since the company thinks on may mot take care of all the ammo you have. Cost of 2 springs against the time, effort and money invested in the reloading, I would do 2 things. I would call either CZ-USA and or CZCustom and chat up one of the guys for their opinion if you haven't already tried that. Maybe they have a better spring or idea? and if they can't help then I'm pretty sure I would just go ahead and buy 2 springs, better to have a back up and not use it than find out that you need to pay all over again for a replacement. If you don't use it then maybe sell it online?
I'm am in no way any sort of gun smith, I'm just throwing in my 2 cents worth from my perspective. :)