I am having the exact same thoughts. Stages has a deal on L-only power meter for 105 groupsets, and I’m tempted to pull the trigger so that I can do power-based workouts outdoors. I want to train for some challenging gran fondos, and the thought of training indoors in the summer isn’t so tempting.
Edit: I don’t race, so I’m on the fence about buying a power meter.
I stopped reading that part as it was a quote from Stages themselves… This is an advert, which is fine, it’s not what I’d call a reliable source of data/information… because reasons. 
My honest opinion on Stages: if you get one, go find a known good power meter to verify it against, whether that is a friends set of power pedals or a good steady state smart trainer like a Neo or Hammer.
If your numbers line up, keep it. If not, warranty it immediately.
I have a Gen 2 Stages and recently purchased (just turned up this morning) one of the Gen 3 105 meters on the deal you referenced. I’ll be interested to see if it’s consistent with the other Stages. I can’t see any benefit to L/R for us mere mortals, what are you going to do with it, try to train your way to something closer to 50/50 balance?
I will keep that in mind. I have a Kickr for comparison
My thinking was that left only was fine for me, because (as others have said) I don’t really care to analyze my l/r balance…it is what it is.
But then it occurred to me that if a 45/55 split (or around there) is quite common, then the total reading for a “double the left leg” approach could easily be off by 10%. Also that inaccuracy from l/r balance likely changes depending on where you are with respect to ftp.
So, I don’t care what the balance is, but I think I do care about my power reading being an accurate sum of both legs.
Just curious, so if folk have an a 45/55 imbalance, what are you going to do about it?
Walk and cycle on one leg to get the weak leg up to strength 
Joking aside, when I had troubles with my knee, my PT tested the power of the three big muscles in my left and right upper leg.
There was a big difference between the left and right leg overall and the ratio between the three muscles in the upper leg per leg.
I did a number of strength exercises to get a more balanced left and right in terms of power and to get a better ratio in my right upper leg.
The numbers were a lot closer to eachother but the left remained stronger, but I think getting that to be perfect is extremely difficult.
I read somewhere that because of how our muscles and brain work, that when you would train one sided in front of a mirror that the other other side will have gains as well
UAE Emerates using L only Campagnolo this year…isnt stopping them from winning races.
Stuff like this makes zero difference to your training and performance for the typical amateur.
I can’t remember where I read it, but someone from Team Sky was saying that when they switched to dual sided meters it actually reduced some of their riders power outputs as they were trying to correct their imbalance.
I use left only but I’ve also used dual-sided on a Wattbike in the gym so I know my split is about 48/52. I’d still quite like a dual-sided meter, but realistically it’s not going to make me a faster rider so until the price comes way down for dual-sided I’ll stick with what I have.
Why?
What will change in your training if you had one value (left x2) vs another (true)?
I ask as this is a bit like Virtual Power, in that it needs to be consistent, but accuracy is secondary from a training perspective.
4iiii you can set the LR percentage in the app
The difference in L/R is interesting. I am considering a L only and I have a kicker at home with a different bike than I use outside. My plan was to use my L only on the trails and have an idea of my power use compared to what I understand my FTP etc. to be from my Kickr. During a race, I was hoping to monitor power and help control my pace. If I’m using a L only and it can be off and under or over estimate, wouldnt that be a negative? Or are typical differences in L/R not significant enough?
I got a quote from Quarq yesterday, their solution costs about $1200, which I can’t justify. However, $320-ish for a Stages L is a good deal, and fine enough for me to train for and pace tougher gran fondos.
If your crank will support it, Powertap has their C1 down to $350 right now. I’ve never owned one before (PM of any kind) and I’m toying with the idea as it’s about the lowest entry I’ve seen. I have a SRAM GPX 110bcd.
Yowch. I can’t imagine any situation that would justify 4x the price for dual-sided power.
Indeed. I would much rather have a single-sided powermeter on ALL my bikes than a dual-sided powermeter on only one.
But I guess some folks have more $ than me :).
Things get a bit more complicated if you already have a PM measuring both sides in one bike. Then getting a single leg PM to your other bike may give you figures that are totally different.
Two things:
Having said that, clearly it doesn’t matter. Zones aren’t discrete, riding more would bring bigger gains than anything else, etc…but if I’m going to go down the rabbit hole…
Just ordered the Stages L yesterday. I was going to do interval training outdoors, but what happens when I try to go back and forth between my Kickr (which measures total power) and my Stages (which doubles L-only).
I guess I wouldn’t be able to do a direct comparison between Stages data and Kickr data, so there can’t be a seamless switch, that is, do one workout outdoors and the next day, do indoors.
I use MTB-style pedals, so pedal-based meters like Favero Assioma are out of question for me.
Maybe I’m overthinking this in my usual fashion. What do you think? (FYI, I don’t race)
Edit: Looking at the price of Power2Max is what’s causing these second thoughts.