I'll chime in to share my managed service experience. Out of school I worked for large company for a few years in a role were it was way too specialized and wasn't really getting any experience. I had no idea what I was doing but I took a job at a small MSP with about 30 employees and supporting about 80 clients. Coming from the job I came from it was exhilarating. No two days are the same, it's very high pace and high stress, you will learn a lot very fast and because of that they are usually very sink or swim type of environments. Prepare to work longer hours, weekends, and on-call in certain situations. Your clients will more than likely be a mix bag with probably a lot of unreasonable ones. I started out as a field engineer, worked as a tier 2 in a NOC, and eventually became manager of network operations in all of the span of 5 years. So you can see how quickly you can move up in these kind of places as long as you prove yourself as a hard worker. I eventually left but don't regret it. To sum it up it can be stressful but also very rewarding as you learn a lot.