I had PSV do a duct cleaning when I moved into my new house, they were great and professional. They do a follow up call every year and see if you need any other services done, so if you don't mind the calls then it's a good reminder.
I asked what other services they do and they said they also do furnace maintenance, so I did that. But this wasn't as great (hence I took away 2 points). My furnace was really loud and they said that the motor needs to be replaced, they also said they will get me a quote on how much to replace it and didn't call back. When I called them a few weeks later to ask they said they don't have the model number and I need to find out the exact model of my furnace (I'm wondering why they didn't write it down when they were here). Eventually I had some other issue with my furnace and I found another company and it turns out the loudness was just the fan, easily replaced and fixed.
So I think their "other" services may not be so experienced, but they vacuum, duct cleaning and I assume carpet cleaning and windows/blinds service is probably top notch, since that's their main business.