I'm of the opinion Harpoon is a disgustingly overtuned item that should be built on virtually every non-illusion melee hero, and needs something like a mana cost attached.

With that said, while I think Jugg might one of the few exceptions... I mean, Jugg can cover the pull with Swiftslash, which usually used to procs basher with enough guarantee and safety that harpoon won't provide, and costs slightly less. Both would be overkill, and I dunno if Echo Saber speeds up farming that well.

But I'll try it. I mean, I think his shard-spin build is dead in the water, and so does Yatoro according to a PainDota video a month ago. His healing ward cd reduction talent is also disgustingly overpowered and has been even before his spin got these nerfs. I think ending early is in the cards and harpoon is definitely way more of a finish early item than Battlefury which is what it would be slotting in to replace. Hmmm. I'll see how it goes.

Now, I'm no jugger regular, but it feels pretty expensive for the stats it gives. You already have the shard movespeed with a free bkb so I feel like you should be able to just run in and ult valuable targets. A basher/skadi usually does the job with more preferable stats.

As you already mentioned, by going echo saber in favor of BF, you're sacrificing a lot of farming ability.

I guess harpoon can be good in some scenarios (like you already mentioned, getting kited by slows/stuns), but I'd ask myself if harpoon is really better in this scenarios than other popular items such as BKB or Manta.

Personally I think harpoon is super niche on juggernaut and if anything I'd get it as like a 3rd or 4th item. Definetly don't skip BF for it.