You should absolutely do it if it makes sense for you, that is, travelling extensively on CX. I was PPS, TG Gold and LH Senator and sent all to Marco Polo club and was comped Silver.
I have since enjoyed more upgrades than I care to count, guaranteed seating (something I used on a number of occasions).
After 3 years as a DM, I will let it lapse however as my business does not take me straight to Oneworld. Star is still most practical in Singapore so I will continue with them. This being said, I thought just being Silver was great for the biz class seating. I loved the CX product but I find the constant stopover in HKG a pain. So back to direct flight or via TG which will save me some time to Europe.