I hear you, Ken. I, too, had a very simple approach for the longest time, but if I were starting now, I might splurge right away for an all in one system to learn on. I also agree with Denny as to why the OP wants to jump into a 3 vessel HERMS system. As I consider it further, the 3 vessel HERMS system doesn't require a two element system, if electric (HLT with HERMS coil and boil kettle) or 2 burner propane (HLT burner and kettle burner), but it typically involves that, which probably means higher expenses.
OP - tell us more about your brewing desires and dislikes and we can probably keep this thread going until you get around to purchasing the set up you want. Thankfully, and really because choice is so subjective, there are so many set ups for you to look at and consider; I would expect that you will find what you want. Brew On, Brother! It really is a great hobby with a great group on this and other fora to choose from.