Power-sweeping what is it, why use it and what are pros and cons.
First if you look through history the sweeping has changed a lot and design technology has improved to make it better, safer and sometimes even less messier; all be it often at a much higher cost for tools.
The older push brushes did work, to a point. But virtually any Certified Sweep today will have and use power sweeping is simply does a much better job.
Now initially power sweeping was okay, but limited in selection of tools for the job. That has changed, with whips, mole brushes, chains, cable, etc.. a lot has changed. From masonry tiles, stainless steel factory built, a tool exists for any job. Rods also come in various sizes for fireplaces, liners, tile breaking, etc.
Frankly none of the earlier brushes are better than the newer ones in 99% of the situations. There are a few situations in very old masonry chimneys where hand brushes offer some value, but most are able to be cleaned as well or better with the proper brush. Part of challenge for sweeps in the variety of brushes needed and the cost which can be huge compared to the old style brushes. Yes into the multiple thousands of dollars!
But do they work! If your sweep does not use then you may wish to tell them to consider as you are not getting best job technology can provide.
As far as pros and cons there are many pros; actually virtually any aspect is better. The cons are cost, the amount of items you as a sweep need to do properly and the risk of damage you can cause if the right tools are not used!
What are best tools. Well there are a few the most well known being AW Perkins and SnapLok. I have had and used Perkins for some time, but have switched to SnapLok as I find they have a much better assortment of heads and overall better suited to do the job.
Can a home owner do it themselves? Difficult to answer but best answer is often not really. The company who makes SnapLok does make a consumer version but only a single whip head is available. The rods are no where near flexible enough to do the job well and the head is suited to a limited chimney design. So it may work reasonable well in some but you have no idea how well in yours and is useless with anything other than the easiest to remove creosote. They may work, they may not do a great job or worst case may cause damage. Use at own risk and with discretion.