LX, without a moment's hesitation.
Yes, the Venturi alone will help keep a well-tuned second stage from freeflowing at the surface (e.g. in a surf entry).
But that's less than half of the benefit of having adjustable cracking effort.
While It's true that with a well tuned regulator, you won't change the adjustment knob at all for the majority of your dives, there are two additional advantages.
First, on a deeper dive with a lightly tuned regulator that makes all breathing easier, the air you breathe is thicker at depth. Therefore, a lightly tuned reg is more likely to freeflow at depth as the mass of air exiting the valve tends to pull the diaphragm in and hold the valve open. With the MBS, it is a simple twist of the knob to decrease that ease of opening. Yes, it is true, you could accomplish some of the same thing by adjusting the Venturi lever. But that won't fix the second benefit of having an adjustment knob:
Second, as the seat ages on a second stage, the point at which the orifice makes contact and seals the valve digs a little groove in the seat. The depth of that groove is like opening the valve by a fraction of a millimeter. That aging process (generally occurring from three to 12 months after service) may allow a reg to freeflow. With the MBS, You can simply tighten up 1/4 to 1/2 turn on the knob to restore the correct poppet spring tension and continue to dive your reg, instead of having it serviced earlier. The alternative, which most shops employ, is for them to deliberately detune the reg so it breathes slightly harder when it leaves the shop, since they know that six months later the groove in the seat will drop cracking effort to something they would like to have provided you at the outset.
Wouldn't you prefer to have light breathing effort at the beginning, and throughout the life cycle between services? Plus have the benefit of immediate adjustment for the density of air at depth?
For me, there's no benefit to having your shop's 18-year-old newly trained technician determine how easily your reg will breathe, with you having no adjustability at your end. Get the MBS.
Yes, the Venturi alone will help keep a well-tuned second stage from freeflowing at the surface (e.g. in a surf entry).
But that's less than half of the benefit of having adjustable cracking effort.
While It's true that with a well tuned regulator, you won't change the adjustment knob at all for the majority of your dives, there are two additional advantages.
First, on a deeper dive with a lightly tuned regulator that makes all breathing easier, the air you breathe is thicker at depth. Therefore, a lightly tuned reg is more likely to freeflow at depth as the mass of air exiting the valve tends to pull the diaphragm in and hold the valve open. With the MBS, it is a simple twist of the knob to decrease that ease of opening. Yes, it is true, you could accomplish some of the same thing by adjusting the Venturi lever. But that won't fix the second benefit of having an adjustment knob:
Second, as the seat ages on a second stage, the point at which the orifice makes contact and seals the valve digs a little groove in the seat. The depth of that groove is like opening the valve by a fraction of a millimeter. That aging process (generally occurring from three to 12 months after service) may allow a reg to freeflow. With the MBS, You can simply tighten up 1/4 to 1/2 turn on the knob to restore the correct poppet spring tension and continue to dive your reg, instead of having it serviced earlier. The alternative, which most shops employ, is for them to deliberately detune the reg so it breathes slightly harder when it leaves the shop, since they know that six months later the groove in the seat will drop cracking effort to something they would like to have provided you at the outset.
Wouldn't you prefer to have light breathing effort at the beginning, and throughout the life cycle between services? Plus have the benefit of immediate adjustment for the density of air at depth?
For me, there's no benefit to having your shop's 18-year-old newly trained technician determine how easily your reg will breathe, with you having no adjustability at your end. Get the MBS.
