I cannot directly answer your question, but I'll tell you my story.
I have an Aqualung Legend set which I bought in 2003.
It is an awesome reg, but as its closing to 20yrs, I think it's time for some new gear, even tho it works perfectly, Aqualung count them as discontinued, and as so, no more replacement parts (only the leftover, what you can buy from here and there)
There are many many older regs which are still used today and those are were beasts and built to last, but honestly, I can't tell they still build regs in the 00s to last, so for the comfort of my mind, i choose the replacement way.
If I were in the same shoes as you, I would choose the Titan, but if I had the luxury to keep both, I would do that till the Legend die. Mine are now starts to show its age by the purge button rubber getting cracky and such.