Titan LX vs Legend LX

I own a Titan LX and looking to upgrade and considering Legend LX, but I am not sure if there is a noticeable difference in the breathing between one and the other to justify the expenditure.

I am also looking at the SP MK25/S600 but not sure about piston vs [FONT=Verdana, Arial, Helvetica, sans-serif]diaphragm, not to mention price difference.

My diving is rec.
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Legend, in theory, is suppose to be delivery more air than Titan. Had a Titan but have yet to have a chance to try the Legend to check out any differences.

SP MK25 is a balanced piston reg. Again, on paper, it is claimed to be delivering more air.

I am also using SP MK25s for my backgas when diving doubles. Compared to my Apeks DS4s (balanced diaphram), which I was using before I replace them with MK25s, it is rather obvious to me that MK25 feeds more air on one inhale.