If your talking just a protective cover not a work tent: I had one professional cover in my life. It was a beauty, access ports, zippers etc. Used it once and decided it was way too much work to deal with. Much easier to wash the boat!
I had the opposite experience. A professional cover keeps everything dry and prevents much frost damage from ice and snow. Plus it allows me to work on the boat when I am not using it without fear of frostbite. Much easier to re-seat a stanchion in a heated waterproof cover than under a drafty tarp worrying if it will rain tomorrow.
I have found on my old boat that a good cover will reduce my spring refit by about 1/2. Idora has alot of bright work so it will be worth it (I hope). I need to start in on riggingparts this summer and there is some rot repair in the dog house to do as well. Covers are a pain to put on and space hogs to store though. All part of the fun.