I tried 3 different tube type dot sights on rifles and was never satisfied with them, granted none were high end. A Vortex SPARC was the most expensive. I have a Sig M18 with the cut for an optic and decided to try a bit better quality optic and bought a Holosun 507 for it.
I found my accuracy improved considerably. Especially at ranges farther than 10-15 yards. BUT... I also had trouble picking up the dot when trying to draw the gun and get on target quickly. I acquired a Glock 19 MOS with the optics cut and moved the sight to the Glock. I found the sight worked MUCH better for me on the Glock.
I THINK that at least part of the reason is that the rear sight has to come off the Sig to mount the dot sight. The rear sight stays on the Glock, and it is possible to use the irons on the Glock if the optic were to fail. I think that subconsciously I am using the rear sight on the Glock as a reference even with the optic. With no rear sight on the Sig, I had more trouble getting the gun on target quickly. I'm sure that with more trigger time I could have gotten better with the Sig. I have no problem going between the 2 designs when using irons.
As a side note, I liked the Holosun well enough to buy 2 of them for long guns. I have one on an AR and another on a 9mm PCC. These are the only dot sights that I found to work for me. Not saying they are the best choice. There may be better, but of the ones I have experience with I like these.
But I do think that this type of sight is the future of handguns. I think they will be commonly seen in the holsters of LE in a few more years. It may take a while before one design proves to work the best and be accepted.