Work of Breathing (WOB) MTX-RC (0.9 J/l) vs MK25 A700 (0.51 J/l)

[AISM]

Hey Guys,
Now I am in market for a regulator and I'm torn between Apeks MTX-RC and Scubapro MK25 A700/S600.
I dive mostly in the Red Sea and warm water, but I want the easiest regulator with the least WOB and high reliability, money isn't a big issue here.

I emailed Apeks to ask for the WOB of MTX-RC and they relied with the total WOB is 0.9 j/l, without specifying the depth, RMV nor temps.
On the other hand, I found a graph showing the WOB for Scubapro MK25 A700 (0.51 J/l) and MK25 with S600 (0.65 j/l).

Apeks MTX-RC (0.9 J/l) V.S MK25 with S600 (0.65 j/l)

Does a human capable of feeling a difference of (0.25 j/l)?
How would (0.25 j/l) impact comfort or anything?

Should the WOB be part of the process of choosing a regulator at all?
I really don't know which one to go with, I like the look of both (tried none of them) and I can get them both serviced locally.

1_s600_a700: PRECISION CRAFTMANSHIP: A700 REGULATOR. INTRODUCING THE A700: SCUBAPRO’s A700 2 ND STAGE Unique work of art Exceptional breathing performance A regulator. - ppt download
2_Scubadiving_MTX-RC: The Best Scuba Regulators of 2020 Reviewed

Based on experience and knowledge, which one do you recommend?

 

[tbone1004]

total WoB is a very misleading figure unfortunately.

Inhalation work of breathing is experienced very differently than exhalation work of breathing. In terms of a humans perception, you can perceive the inhalation differences far easier than you can the exhalation differences for two main reasons. First is that the body is used to "blowing" and not so used to sucking. Whistling, talking, coughing, all sorts of things are done every day that create positive pressure in the lungs. You never really suck on anything using lung power *sucking up a straw is mainly suction created by the oral cavity vs the lungs* and it's a very unnatural experience. The second is that very few divers are ever truly flat in the water and even fewer are head down so you are getting an exhalation "assist" by the differential pressure in the water column that will squeeze your lungs out for you.

The image quality posted isn't really great, but it appears that the inhalation work of breathing is about the same and the big difference is the area under the curve for exhalation which is not something I would personally worry about.

 

[Ian Fatzinger]

I have both regs and I wouldn't say that I can distinguish between WOB. Both are incredible

 

[AISM]

I have both regs and I wouldn't say that I can distinguish between WOB. Both are incredible

At what depth and temp you dove both of them?

Which one you find better in general?

 

[Alaskan Scuba Dude]

Should the WOB be part of the process of choosing a regulator at all?

How healthy are your lungs?

 

[Ian Fatzinger]

At what depth and temp you dove both of them?

Which one you find better in general?

Both down to 45m, water warmer than >75F. They are both incredibly tried and trusted regs

 

[Still Kicking]

Both are great regulators in terms of performance and reliability. I highly doubt you will tell the difference even side by side. People get way too hung up on the WOB numbers, which are for the most part splitting hairs.

Those magazine reviews are really laughable and generally reflect the volume of the advertising buys. Do not put any weight in them.

 

[AISM]

total WoB is a very misleading figure unfortunately.

Inhalation work of breathing is experienced very differently than exhalation work of breathing. In terms of a humans perception, you can perceive the inhalation differences far easier than you can the exhalation differences for two main reasons. First is that the body is used to "blowing" and not so used to sucking. Whistling, talking, coughing, all sorts of things are done every day that create positive pressure in the lungs. You never really suck on anything using lung power *sucking up a straw is mainly suction created by the oral cavity vs the lungs* and it's a very unnatural experience. The second is that very few divers are ever truly flat in the water and even fewer are head down so you are getting an exhalation "assist" by the differential pressure in the water column that will squeeze your lungs out for you.

The image quality posted isn't really great, but it appears that the inhalation work of breathing is about the same and the big difference is the area under the curve for exhalation which is not something I would personally worry about.

I upload the MTX-RC image again. And added a ANTSI loop for the MK25 S620TI (at only one depth and one breath rate).

Does the loop/data differ widely between depths, so manufacturers would choose the best combinations between depth and breath rate to yield the best loop/data for marketing.

 

[AISM]

Both down to 45m, water warmer than >75F. They are both incredibly tried and trusted regs

Awesome, did you find that the second stage of MTX-RC is heavier than S600/S620ti in the water?

 

[AISM]

How healthy are your lungs?

Pretty healthy I think, don't smoke