GTK and BearShare 5 appear to have some things in common. Not good things from one point of view. I consider GTK to be the most advanced Gnutella client, yet some aspects of its behaviour hint at either old technology and/or poor gnutella manners to say the least.

I'm one of the very rare people who instead of spending my time viewing downloads or search results, I spend most of my time viewing uploads. I share a reasonably large number of files. Yet I don't consider myself a good file-sharer. I don't like to see misbehaviour or greed among hosts downloading from me.
If I feel a host has already downloaded enough files of a particular type for the session (usually over a small portion of that time), then I will restrict that host by reducing upload slots or speed or both. (I usually exempt music files unless it's extreme.) I suspect most people don't take notice or much care of their uploads.

The Issues:
I've noticed GTK and BearShare both have something in common. BearShare will often appear to only be downloading one file at a time but each subsequent file begins instantly thereafter. Usually no queueing at all. Which makes me wonder if that person is really selecting the downloads so coincidentally & instantaneously after the other finishes or the files are being queued for download on their client side but not in the uploader's queue. GTK appears to do the same thing. However GTK will also download multiples at once.
The Demon:
The downloads finish & the next starts so quickly that other hosts files waiting in my upload queue never get a chance to start their downloads. GTK might take all available upload slots & the cycle never finishes leaving other hosts waiting forever in the standard queue.
The Demon's bite:
So it appears I may have a very greedy host. If I change upload speed or reduce upload slots, this appears to make no difference. GTK (and BearShare 5) will continue to download at the rate they started their very first download at.
Extreme measures:
Ban the host. Makes no difference. The BearShare or GTK host continues to download more & more. Only a 3rd party ip blocker stops them. Something I use very reluctantly. I cannot say this is true 100% of time, probably 90% of time the GTK or BS host ignores the changes from the uploader's client on the other side of the fence.

It's almost as though GTK has its own non-Gnutella technology that by-passes standard Gnutella listening rules (and queueing rules.) (I remember Morpheus being a bad host for respecting uploader's queues. But this is a little different. Morpheus was a queue hopper that appeared to somehow bump each host just above it in the upload queue off the list one by one every 30-120 secs or something. Those bumped off would return at the bottom of the queue.)

I've noticed this issue using both LPE & WireShare on the uploader's side of the fence.
The BearShare issue I noted several years ago to a couple of moderators who were BS users who probably thought I was crazy.

Downloading issue:
If ever there's a host struggling with downloads (usually videos), it's often a GTK host. Almost as though they're using an old technology, but that is obviously far from the case. lol I can't remember the specifics though I've seen it a lot over the past year or so and many 'different' GTK hosts. This issue is different to the queueing issue, there seems something wrong with the GTK client side's download abilities of large files from WS/LPE.

I'm not expecting anybody from GTK to take notice of this post (too busy with g2?) but thought I'd make a note of it somewhere. Perhaps someone else 'not' using GTK-Gnutella has noticed the same thing.

I was not sure where to post this. So if it's not appropriate location, ask a Moderator to move it.