Two similar domains - a test?

Hi

I have acquired two long-standing and strong domain names in the niche which I operate, but with slightly different links to keywords for related (but different) services. Demand for both these services is similar.

Both are a blank canvass and I was thinking of developing them simultaneously with one being content 'heavy' and the other more slimline, light, lead generation focussed. I'm simplifying but one as 80:20 but the other as 20:80 - hope that makes sense!

Anyway, just wondering what people's thoughts are on which might work best?

Part of the reason for me to do this is as a test.

Thoughts and ideas welcome - thank you.