Stacking up tolerance and core cost still seems far superior than spam-converting at high ToTF when it comes to blobbing; besides, Sunni with all that Orthodox next to you is really powerful (super cheap tech). All that together and your MP usage should save you enough to make BYZ's stream of free MPs not as ridiculous. The direct combat boosts are also pretty damn massive and the culture group is obnoxiously big.
Of course, BYZ gets a LOT of free tradition on the early/mid game, but frankly that's not enough to beat the ottomans' much more insane army boosts. The free starting cores just about everywhere around combined with a 5/5/6 ruler should bank you a tech lead to break any opponent early on easily. And that's assuming there ever IS an opponent, given the typical final boss is, well, you.
I can't see BYZ as a "buffed Ottomans", for they lose generally everywhere:
-Weaker armies
-Smaller navy
-Far better starting position, including a good 300 dev difference in total core development and a 5/5/6
-Government that guarantees good to amazing rulers consistently, combined with the sunni/dhimmi tech cost and CCR, just stomps out the MP events
The one thing Byzantium arguably does better is silence rebels (with Religious) due to super cheap -40% stabcost, 9+ ToTF and loads of high-strength missionaries, but the turks aren't too far behind with Humanist(-Offensive)'s -10(/15) years of separatism, -2(/3) global unrest, no intolerance of heretics, and tolerance of heathens pretty much on par with ToTF.
Don't even get me started with the "siege forts like a maniac" age ability that assures no fort is going to lock you for too long in the first age.