From a mechanical standpoint the Legend and Titan first stages share the same basic seat carrier, orifice and diaphragm design and any difference in performance is not going to be noticeable. Both are essentially rewarmed and slightly refined Conshelf first stages.
The adjustable inhalation effort on the Legend is nice to have however and is worth the money. It will allow you to fine tune the cracking effort to the minimum you can achieve in any particular position. It will also allow you to compensate for minor break-in and wear of the LP seat and will probably save you a trip to the shop over time.
Someone posted previously on the Legend's performance on the Monitor, but that has a lot less to say about reg performance than you would think as helium mixes flow through regulators much better than air.
The poppet (or shuttle valve as Aqualung calls it) in the Legend second stage is a one piece version of Scubapro's older poppet design and the air barrel in the Legend second stage is very similar to the air barrel in the older Scubapro G250. Not surprisingly the two second stages perform essentially identically.
Someone also posted that the Legend at one point had the lowest WOB in the world. At the level of design you find with top end regulators, it the tuning and adjustment that make the difference in terms of work of breathing. I am always very skeptical of a WOB number as:
1. It is an average of inahlation and exhalation effort and a second stage that inflates the diver with positive pressure will offset a high exhalation effort and still show a low WOB.
2. At best it is a quantitative measure that says nothing about the smoothness of the airflow.
3. on a top end regulator it is totally very dependent on the adjustment of the individual regulator and no third party testers ever look at whether the reg tested is properly tuned for peak performance.
The legend is a good cold water reg, but it has frozen up in tests in very cold water at 165 ft after about 30 minutes. The Scubapro Mk 17 finished the same test (200 minutes in lenght) without freezing and the Mk 17 has a higher flow rate of 177 SCFM - more than enough for any diving situation.
So in short, I like the Legend second stage stage, but it offers no advantage over a Scuabpro G250 or S600 (and all three pale in comparison to the discontinued Scubapro D400 which has the most natural breathing traits of any reg I have ever owned) and the Scubapro Mk 17 is a better first stage than either the Titan or Legend.
