A blow torch is a bit dangerous. I like the heat guns, super charged hair dryer from hell. These work really well.

With 20+ layers I think the Peel Away would be easier. With heat alone, this would take a while. At least with the stripper you might not have to work as hard.

I have successfully used a blow-torch (rusebud multi-flame torch tip) to remove paint from wood buildings. Keep the torch moving back and forth and have a putty knife or scraper in your other hand. After heating about a 6" square area use the putty knife to scrape off the old paint. Have a water hose and a fire extinguisher nearby. I use a spray bottle filled with water to spray water on each area that I heated and scraped.

I have used and seen people using a blow torch, I do not recommend this method. As Karl had mentioned it is extremely dangerous. It only takes one small ember to drop somewhere unseen and several hours later Poof. I have seen it happen and if the home owner is around they may have a stroke or heart attack seeing you torching their home.

I also Recommend using a heat gun. As Karl mentioned it has more then enough heat to remove the paint whether it be one layer or 50 layers.

The easiest way to use it is to heat a small area use a putty knife to scrape the paint off. You can also spray a bit of water on it which will create a bit of steam and help loosen the paint.

Using a paint remover is probably the quickest way to complete the job. Although I have always been fearful that using these products, tend to seep into the would and when your scraping to start to remove part of the wood along with the paint. So if you do go this route be sure to not gouge the wood. Yes I realize you are a contractor and have done this work for many years, I am simply giving a heads up, not trying to talk down. So you don't make some of the mistakes I had made, years ago when I first started out in the Painting and Construction Trade.