me too sometimes feel not really happy with only single ss - i need to make choice what to put under ss and what will be air/water cooled. Chiller is more flexible but more expensive and requires much more service. And it must be really powerful. So, if i had enough money i would choose:
1. 2 ss - one for cpu, second for gpu
2. several waterblocks/pumps and powerful chiller
3. one ss
4. week chiller