I have Xpel on my 2016 Crew Cab Silverado. I had the front bumper, headlights, fogs, mirrors, half the hood and fender, A-pillars, and leading edge of roof. I also had the vehicle polished (One step) as it had been sitting on a dealer lot for 6 months and needed it before applying PPF. The vehicle was then had OptiCoat applied that lasts for 5 years. I paid $2000, but I know I got a discount since I bundled some services. As with a white vehicle, the same probably applies to black as well. I had to take my truck back as I had a few places on the bumper where bubbles didn't come out after two weeks, and there was a few pieces of trash under the film. And this came from a reputable place that has been detailing for 20 years.
The pro to me if I was a client is that you would be offering a one stop shop. I found one local place that had higher prices for polishing and coating, but didn't do PPF. The owner told me he would do the polishing, drive the truck to another shop to have a cheaper PPF (SunTek, not Xpel) installed, and then have the truck brought back to apply CeramicPro. I didn't like the idea of two places doing the work, as if I didn't like the workmanship, who would be to blame. Also after polishing, the vehicle would have to be re-prepped since it would have been drove about 10 miles to the PPF shop.
The con for you would be the initial investment and possible learning curve. I have seen your work posted on this forum, and I would say you have the knowledge and experience to learn quickly. Take some classes and get certified.
If you have a higher end clientele, I would say go for it, as it shouldn't take long to pay off for your investment, as I know my dealer charges roughly $3-5K to wrap the whole car depending on size. Xpel shows prices for templates for each vehicle they offer. Based on my experience, they are quite high based on their website, but my dealer seemed to charge less than the template price and that included installation. I wish you luck on either way you proceed, and keep posted on the awesome work you are doing for your clients.