Colemak will do 2 things for you:
1. Cut the distance traveled by your fingers by almost 1/2.
2. Reduce same finger ratio (or else remove the need of many non-standard fingerings) and balance load between the fingers.
Although you might think this will greatly improve your speed it wont.

At this point/speed it is more about comfort and especially if you experience pain after long periods of typing. If you don't want to be frustrated for couple of days and put up with not having colemak everywhere and you find Qwerty comfortable enough there is no point in switching.

That said, I have no doubts that given practice you will be able to achieve 140 wpm with colemak if you focus on practicing speed typing. But in general your speed will just plataue no more than 10 wpm adove what it used to be before as high speeds rely more muscle memory than anything else.

I'd say it's abosuletely worth it for the added comfort of your fingers being more relaxed and minimizing wrist fatigue and pain.

Before I started my Colemak journey, I tested my Qwerty speed on 10fastfingers a couple of times. I scored about 50-55wpm using a semi hunt-and-peck approach that I had developed adhoc over 30 years. My speed now after learning Colemak + proper touch-type technique is about 65wpm. So certainly a little faster and gradually improving still. As others have said though, the main benefit gained is comfort - the speed increase it's a just a nice side effect.

When using Colemak it feels like you are using a keyboard in a way that makes sense, as though the keyboard is no longer working against you. For a tool I use for several hours almost every day, it's amazing to think how inefficiently I had been using it for so long!

i fell into the same camp as steve - so it made a lot of sense to pick up an alternate layout at roughly the same time as learning to touch type for the first time after decades of hunting and pecking.

if you are already that competent at qwerty, and not really suffering any consequences then its a hard sell for an alternative layout. 110-130 is *really* fast.

I probably wouldn't bother if i were you, alternative layouts are a massive pain from time to time, maybe just revisit if you suffer any RSI down the line..

For what it's worth, I haven't yet reached my old QWERTY speeds after a year of Colemak. I was at 90-100 wpm in QWERTY, am up to 70 wpm in Colemak.

My only thought is that 70 wpm is "good enough" -- it's not like being stuck at 40 wpme. I developed that QWERTY speed when I was much younger, too, so maybe it's something different about me or my life.

I think I am also making slow improvement, but at this point it's very slow.