If you want flex, don't go titanium. A ti nib is not flexible. It is soft. It will bounce like a big 18k nib, giving you a lot of cushion in your writing. But it's very easy to spring if you try to get line variation out of it. I have an EF and I don't push it much beyond an M.
I personally prefer gold to titanium, but in a mid tier pen like a ranga, a Ti nib really is kind of the perfect pairing. So it's worth considering as an upgrade to steel, but I personally don't consider it a substitute for gold.