The only leaking I've had is like
@SonnyCooL, but it's been my fault. No liquid coming from inside, though the 510, etc.
I've pulled my bottle out a few times to find a small amount of liquid behind the bottle, or inside the mod compartment, but not coming from the closed internals of the box. What I found was mine was due to not having the bottle cap screwed tightly enough down. Even just a little liquid slowly coming out the bottle threads can spread quite a distance inside the mod.
If I screw the cap down tightly and clean the outside of the bottle well when refilling, no issues. I fill the bottle the old fashioned way, not using a refill bottle. It's pretty painless to do without the refill bottle with this mod and the bottle system. I've been using mine today for two months with no issues.
As far as batches, I think all of the ones being sold are still labeled as the original batch date of 4-15-18. Any product will have a few that slip through QC with issues, it's impossible to catch them all. However, I've seen very few complaints regarding the Pulse 80 compared to other squonk mods.
I have a large number of backups for this mod (my favorite squonker) and I will be getting a few more at some point. Seems like a very solid and inexpensive regulated mod. Even after two months of use, I'm still in love with mine.
Not sure where you are seeing these reports of leaking inside the mod, perhaps reddit or another forum? I believe there's only been one instance of this here if you review the thread we've got going for the mod here. Lots of folks here own this, very few complaints.