I can't say if any a dynamic bike fit, Retul, or cleat shims are "worth it" as those are very personal decisions in terms of the money you're willing to part with. But let me just chime in on an overall bike fit experience that I've had.
So I've purchased three bikes in three months (got into cycling hardcore, was bitten by the bug). You can see them all in my signature.
First bike was a fitness (FXS6) and, a six weeks later, I bought a road bike (SuperSix). Both from the same LBS. They helped to ensure that I had the right frame, that the seat height was correct, and also helped me install SPD cleats and set up the angles of the cleats in my shoes. I thought this was very good service. I had heard about a full bike fit, but that was an additional $95. So not quite to the level of a full dynamic bike fit but they said to allow an hour for it. I passed, since I was trying to be fiscally conservative.
Fast forward six more weeks to when I bought my Giant TCR. I had fully been bitten by the riding bug, and had also gotten a bonus from work. So I splurged because the test ride convinced me it was superior to the SuperSix in every way. The guys at Giant Santa Monica included the bike fit, it took probably about 75-90 minutes (I didn't time it). A lot of observing me riding, measuring limb angles and lengths, stretching, then adjusting the bike, rinse and repeat. After about 5-6 cycles of this he had me at my most comfortable (same frame on a trainer stand). Then they cut my seatpost and made all the adjustments to the new TCR.
It was a small miracle in terms of comfort, ride improvement, and power transfer. I instantly felt faster and more comfortable than my SuperSix. Sure, some of it was a kick-a$$ bike but some of it was the fit as well. They gave me my fit measurements in case I ever bought from another bike shop and wanted to have them set it up to that spec.
A couple of weeks went by and my TCR felt miles better than my SuperSix, to the point where I never rode the SuperSix. Then the other day, feeling a bit punchy, I decided to experiment on the SuperSix and try to get it as close to the fit measurements as I could. I knew that even if I screwed it up, I'd not be out of commission since the TCR was always there.
I flipped the stem which lowered the handlebar a couple of cm. Then I slightly changed the angle of the bars to more closely match (visually at least) the TCR. I adjusted the saddle height (which, credit to the original LBS was fairly close, within a cm or so of the fit result), and moved the saddle forward a bit to match the reach. It wasn't perfect, but it was a lot closer.
I then rode it. The Cannondale felt like a different bike. Don't get me wrong, I still prefer the TCR, the geometry, power transfer, and comfort still exceed the SuperSix. But whereas before I would have said the SuperSix was 60% of the bike the TCR was, now I'd say it was closer to 75%-80%. Just the small changes to the fit made it feel much better to ride! Whereas before I was thinking of stripping it for parts (and keeping the Di2 transmission to transfer over eventually to an aero frame), I now will keep it intact for the time being as a backup road bike until I go with a new frame maybe in a year or two.
So I'm a big believer now in bike fitting, at least the mid-level fit that takes an hour or so to do.