I was real nervous about the step from Aeropress to espresso, but I knew that I liked good espresso from cafes nearby so I eventually took the plunge.
I got a basic Breville grinder/espresso machine, which makes decent coffee, not great, but good enough, but I really prefer espresso to other coffee drinks, and my wife loves it when I make her a latte, so overall it's been a huge upgrade.
If you prefer espresso or latte style coffees, or you just enjoy trying new sorts of coffee things and tinkering with grind size, then an espresso machine will be great, otherwise you are wise to stick with the style of brewing you know you enjoy.