Just my 2 cents for what it's worth...
My background: I'm a software developer and have been "playing around" with home automation for about 18 years now. I did my first house back in 2000, wiring and all, using some of my own programming and a Russound platform with 11 zones. At the time I did it on my own, including the wiring, due to a lack of qualified people in my market at the time.
My last project: We just purchased a new house a year ago and did some remodeling. I GCed everything for the remodeling. The smart home portion of the project included: 20 audio zones, 8 4k video zones, a theatre, lighting control, integrated alarm, etc. I considered doing the smart home work on my own but I went with a local company.
Why did I use someone instead of doing it on my own?
1) Someone that does this all the time knows the nuances of the various equipment available, how well it works together, and if the equipment can accomplish what you need today, and in the future.
2) When you have problems, notice I didn't say if you have problems, you have someone you can reach out to that knows what they're doing. In addition, they have more contacts than you do and more knowledge than what you can find on a forum. There are some really smart people on these forums but someone local is invaluable.
I don't regret for a single second going with someone else to do this integration.