not if it works, there really is no "wrong system", there is more or less features now thats all, and depends on what you want out of it.
for someone who changes devices constantly a variable voltage is more preferred because each device is a different resistance and needs different voltage but if your the type who screws on a clearo and uses just that all day, then its not needed. once you know where the sweet spot is, say 2 ohms for you then you can just buy more stuff thats 2 ohms.
In the end its always wise to buy a few more things, especially batteries for back up. when that time comes buy something like an ego twist or vision spinner and then you have the VV to play with also.
you can never have enough backups- we cant run to walmart if a battery dies.
if your just starting out this system is perfectly fine, will work, and be relaible, but this is the first step of a very large flight of stairs so to speak, if you choose to go further with gear.