Ok.. so after a (very) short drive we still have some issues, however the noticeable issues are now mostly rattles and squeaks - it is early days though, so I'll see how much the box degrades over the next few days (if at all).
This box feels quite different to the last three - the shifts into first, third, and fifth seem to be a little woolly.. but not clunking or grinding as yet. Second, fourth and sixth are still noisy but so far I've only noticed one instance of grinding (and only minor - so could have just been that a week in a Kia -fkn kias- has thrown my timing way out!) and one brief instance of being locked out of first (went straight in on the second attempt as opposed to banging it against the gate for 30 seconds and looking like a ########). Shifting in general feels a little lethargic though there is less question about gear selection so it's all swings and roundabouts I guess. It's also quite difficult at times to determine the difference between a gearbox that is clunky through faults from one that is clunky by nature, though I do tend to normally lean to the latter so as not to assume there is a fault. I'm pretty much resolved to the fact that (most) clunks are now normal, but grinding is bad, so if that starts up again, there is clearly another issue.
There's still plenty of backlash in the driveline, though doesn't seem to be as violent - not jolting the car around but I will take the car for a good run tomorrow with a good mix of slow and fast driving - and plenty of car park trawling (the time when the backlash is most violent) to really test it out.
So aside from the rattles (some are quite violent), so far so good, I guess. I'll be running the car up again at the end of next week for an evaluation and to have those rattles seen to - again.
Fingers crossed, huh? I'll be remaining neutral on the subject until it's clearly still rooted - or clearly resolved.