A lanyard hole at the top of the unit.
It would be really, really handy to be able to have a wrist-strap to secure the iolite like a digital camera, or hang it around your neck.
Some kind of locking mechanism for the bowl
Every newbie I've seen picks it up by the mouthpiece stem unless shown how to hold it. But even after using it for months I still occasionally bump it and spill out the bowl into my pocket or worse.
Replace the white mouthpiece tip with a black version.
White draws too much attention to an otherwise stealthy tool. It would otherwise look like a mobile phone or walky-talky, but the white tip says otherwise and people can't as easily rationalise what they just glimpsed in your hand.
Improve heat characteristics of the entire mouthpiece.
Even with the white mouthpiece it still gets way too hot for my liking. I guess this is a toughie as it'll be a compromise with vapour re-condensing.. but hopefully there is a solution that won't compromise vapour quality and delivery.
Switch all mouthpiece attachments to the same slot-in join rather than threaded (aside from the bowl)
Aside from the bowl stem, it'd be nice to have a standard slot-in joint with a variety of different stem sizes not just 2 sizes. This would also make it easy to join them all up in different combinations for even more choice in stem length.
Butane window?
Personally this was my #1 observation, but in reality I don't need it and would never check. I just refill it as required, or top it up if I know I'm going to be using it a lot that day.
Smaller case
The all black case without the i-inhale logo is an improvement, but it could be made shorter. There's a lot of room above and below the iolite which is not able to be used. Perhaps on the opposite side there could be elastic straps (perpendicular to the iolite's strap) to safely hold mouthpiece stems or even have these beside the iolite in their own strap.
There's a lot of wasted room which can't easily be utilised. The magnetic pocket is great, but if it was full height then you could store bulky objects at the bottom and top using the spaces around the iolite when closed. Just seems like you should make all space useful, or make the case smaller and less bulky.
A hard, moulded case would be awesome. I find I don't use the soft case at all now, just carry the iolite and a stem in my pocket. Having a lanyard hole would mean I'd carry it around my neck and use a wrist-strap while using it... so yeah the case is not useful enough or small enough for me to want to use it while travelling.
More separated exhaust/intake
I'm not sure much can be done to improve the location of the air intake, but separating it further from the exhaust (if possible) would be great. I've gotten into the habit of only inhaling while the unit is not exhausting but if it's possible to move them further apart then even better.
Stainless steel pin
Same as the previous comments, and it'd be nice to improve the durability of the thread and perhaps you guys could try a variety of different heat pin shapes and sizes?
Stainless bowl could be made liquid safe
I noticed some of the newer beta models have a rounded bottom for the bowl - seemed to be one piece of stainless. Something like this to vape oil or hash (as long as the unit is kept upright while in use and cooling off) would be a really great bonus.
Improved bowl design
The bowl design isn't great. It's relatively difficult to pack a new bowl or to clean out an old one. The plastic around the bowl often catches what spills over and it's a pain to clean that out other than half attaching the bowl and blowing it out. I've started filling the bowl on the main unit rather than the lid attached to the mouthpiece, the whole upside down thing was a pain and I find I get better heat exposure filling it bottom up. But there's got to be an easier way of filling. Like some of the whip style vapes it would be nice to be able to suck up your herb like a straw through the mouthpiece.
90 degree adapter for mouthpiece
It'd be nice to have a 90deg adapter for the mouthpiece. It could then fold away alongside the top of the unit when not in use - this could even be incorporated as part of a bowl locking mechanism. Then when you want to inhale rotate it 180deg out. Could make for improved stealth and let you fold it away and stick in a pocket quicker and it won't be as uncomfortable. I prefer removing the entire stem, but if I could fold the stem back then just as good imho.
Gnurled grip on the first mouthpiece stem
To make it easier to unscrew the mouthpiece add a gnurled grip - just for the first one, otherwise all slot-in joints as above.
Temperature influence, if not control
I'm no expert on bi-metallic temp control, but if it was possible to slide a switch that exposed a heatsink somewhere in the temperature path then it would be possible to slide this into one of 2 positions giving the normal 190degC or when enabled a lower temp such as 180-185, kind of a brute force heat sink approach rather than adding any electronics. Part of why I like this unit is there are no electronics, saw a post of a guy dropping his in a spa - dried it out and all working fine - that convinced me
Ummm.. will think some more I'm sure I've had other thoughts on this :-D
And yes I'd love to test out future beta units :-)