Hiya!
I like it...but then again, I've used the "7 magic item on your person maximum" rule from the old Bard Games RPG The Arcanum. (yeah...7 magic items maximum on your character...otherwise they all stop working for you).
So far, nobody has ever gotten to the point where they had to decide to attune or not to an item due to having more than 3. Highest level campaign has been 6th level though...so there's that. In that campaign I also had a house rule that never came into play where a PC could get a "magic-item-set" that was created to be used together. Individually, the items were fairly minor, but once they were all together, their true power came to bare once a PC attuned to them. These items were all then "one item". A character could have the "Thasslean, Sword of the Waves [cutlass +1]", then get "Thassleans Guard [Shield +1], and finally acquire "Thassleans Helm [Helm of Comprehend Languages]". Once all three were attained, they became known as "Thassleans Trifecta", where they all together only counted as a SINGLE item for attunement. They also got other abilities (Sword of Speed, Shield or Reflection, Helm of Fish Command) added on to their original.
This made for one "super item", but it all would add to the uniqueness and history/background of the campaign world (not to mention player pride if he/she managed to get all the items in a 'set').
^_^
Paul L. Ming