As a general rule, the earlier the Colt the better. Early DS’s have knurling, serrated triggers, a gas cut above the barrel, these little things were dropped in later production.
The earliest DS’s have a slender grip frame, notice how your Tyler-T grip fits, that T Grip was made for later DS’s.
The later DS’s do have thicker, and in my opinion, better sights. The grip frame area is less likely to pinch at the top, and of course, the ejector rod is slightly longer.
It is kind of a toss up of which is better, 20’s/30’s/40’s DS’s or 50’s/60’s . There is one absolute, the 70’s and up DS’s are horrible. If you look at the internal parts of pre 1970 DS’s, the parts are well machined, hardly any file strokes, defined contours and edges. It is apparent that the parts were almost perfect when delivered to the fitter’s table. Must have taken just a file stroke or two to have a perfectly timed revolver. The 70’s and up Colts, the internal parts look like they were carved from soap chunks. The poor fitter must have been handed slab metal chunks and had to remove a lot of material to get the contours and edges that are needed for the lockworks to function. That tells me the process controls and machines had broken down and Colt was focusing on shiny surface finishes to sell guns, and slighting the quality of fit for internal parts, which is important for reliable function, but you can't see unless you take the side plate off.
