Here is my take on the current Aqualung lineup:
Titan (2010 - Present):
Current Titan uses the same body as the Core, Mikron ACD, and the New Helix/Helix Pro. The main difference is that the current version of the Titan does not come with ACD or in a cold water/Supreme version. the Titan 2nd stage is a basic unbalanced 2nd stage that shares everything but the name with Aqualung's budget friendly Calypso 2nd stage.
Core (2015 - 2020/2021):
The Core was recently discontinued. The 1st stage came with ACD and came in a cold water/Supreme and non-Supreme versions. The Core has a balanced 2nd stage and an adjustable venturi knob. The difference between the regular and Supreme 2nd stage versions is the Supreme includes a "heat exchanger" at the hose connection, a removeable lip shield on the mouth piece, and the addition of a snowflake next to the logo on the faceplate/purge button.
Mikron ACD (2018 - Present):
The Mikron, reintroduced in 2018, is the same as the Core except it does not come in a cold water/Supreme version. Further distinction between the Core and the Mikron are in the 2nd stage where although some parts are shared with the Core 2nd stage, the overall design along with some of the parts are scaled down to make for a smaller and more compact 2nd stage...it too sports a venturi adjustment. The Mikron 2nd stage has been relatively the same since 2008 with only the graphic on the faceplate/purge button being changed. While this regulator set is good for everyday use, it is primarily marketed for those looking for a smaller package for dive travel....though it should be noted there is no weight savings on the 1st stage compared to the other models.
Helix/Helix Pro (2021 to Present):
The Helix 1st stage can be viewed as the replacement or actually a re-badged version of the Core. It comes with ACD. The difference between the Helix and the Helix Pro is that the Helix does not have the cold water environmental seal and the Helix Pro does...the Helix Pro would be the analog of the Core Supreme. From my understanding, the Helix 2nd stage is just a rebadged version of the Core 2nd stage with the main difference being a new faceplate design. The Helix Pro, like the Core Supreme comes with the heat exchanger at the hose attachment, and a removeable lip shield. Both the Helix and Helix Pro have the adjustable venturi.
Since all 4 models use the same 1st stage body, they all come with 4 LP ports, and 2 HP ports.
Should you pay an extra $150 for the Helix Pro?
That is personal decision...do you dive in cold water (less than 10c)? on a regular basis where you are concerned with regulator freeze-up? BTW, the Helix Pro is only @ $50 more expensive than the Helix as listed on the
Dive Rite In Scuba website
I used to regularly dive in the winter where water temps were often 5c or less. On my primary cylinder I had a pair of Mares MR22s coupled with Abyss 2nd stages. On my pony bottle, I had an unbalanced piston Calypso 1st stage with a Calypso (same as current Titan) 2nd stage....none of my regs had cold water kits and I never had any problems.
Since the first stage is functionally the same across the different models, it really comes down to whether you are driven by budget or performance. I would recommend the Titan if you are looking for a solid performing reg set but your budget is your main consideration. I would also recommend the Titan if you were into self-service and did not want the added detail/frustration of dealing with the ACD system when servicing. The minor issue of not having ACD can be addressed by adding the parts if one really desires this feature (best to do by buying the yoke version and then swapping in the Core/Mikron DIN kit @ $65 +/-).
If performance is your primary consideration then I would recommend the Core or the Helix models. While 1st stage performance will be unchanged, the pneumatically balanced 2nd stages will breath a bit better all around and should function better than the unbalanced Titan 2nd stage as you breath down your tank. Now that Aqualung has put out the Helix/Helix Pro, you may be able to save money by looking for deals on the Core/Core Supreme....but if time is valuable then skip the hunt and just go for either of the Helix models.
Hope that helps.
-Z
Edit:
*The 2nd generation of the Titan was the Titan LX. It was discontinued in 2014 and replaced by the Core in 2015...the main update was a change to the current body design that the is shared among the all the models listed in this post, with the major update being the addition of a 2nd HP port. The Titan LX 2nd stage was a pneumatically balanced design...which essentially became the Core when it was introduced.
**There was a design patent infringement issue with the post 2010 Aqualung 1st stage body used for the Titan, which as stated is common to all the 1st stages discussed in this post. Aqualung made a modification to the 1st stage design in 2013 which continues to be used on all the models mentioned through the present.
