Easy solution for solo vs competitive balance: micropatches
Professional play is one patch behind live play. This gives us a very easy solution to pro balance needing to be different from regular balance. Just produce a patch that balances for competitive play with a bit of lead time before tournaments and is only live for a day. Then it can be patched back to the regular version. The pros will then play a patch behind like they usually do, but they can have their proper balance in tourneys and the rest of us can have our proper balance 95% of the time, with one day every few months where we get a taste of pro balance ("wow, how do those people make Kalista work? I gotta watch that LCS!"). It's not as good a solution as maintaining two separate versions of the game, but it would be significantly better than the compromise we have now, with some strong competitive champs being garbage in low-level play and easier champs being weak in coordinated teams.