The only meaningful difference introduced by blk 3 seems to be under the surface, in this case most likely limited to radar and associated software upgrades to allow for newer weapons. That's about it. But for anyone with no real delusions of how much Pakistan can and should spend on any JF-17 upgrades, this is pretty much an exercise in maximising the effectiveness of the fighter while controlling development and procurement costs. It's fair and expected and reasonable. Dreams of VLOing a relatively outdated and aerodynamically reserved frame would actually be a foolish enterprise. If blk 3 can track and fire PL-15s at maximum missiles travel ranges, along with any more bonuses, it's a winner for the money.
Where it actually could get interesting is electronic warfare equipment but we'll never learn of that.
