I have two versions of these; 1 for the 600ml and 1 for the 900ml Evernew pots.
The snaps have held up just fine on a 2 weeker and other various 2 and 3 day trips. I am careful when unsnapping though.
Efficiency wise, I’ve not done any real metrics (i.e. not plugged anything into spreadsheets) but I have found that my MYOG kojin ‘screw top tin’ type burner boils a mug of water (got to be a mug for tea – I don’t do cups of tea) in 6-7 mins on about 12-15ml but there is some soot.
That compares to my MYOG cone with the same stove but with an Alpkit/Toaks 750ml in a slightly longer 7-8 mins with the same amount of fuel (bio-ethanol). Again there’s some soot suggesting not enough air or the pot-flame gap is not right. Part of that difference is likely to be the pot base diameter (I am guessing).
Toaks Siphoon is quicker and cleaner coming in at around 6.30, same fuel, same mug. Little to no soot.
The fastest, cleanest combination I have found is the Trangia burner with the Vesuv. Again, same mug and around the same fuel (weighing the burner before and after rather than measuring the amount meticulously over multiple runs).
I have ordered a couple of lighter Trangia burner clones (still with screw tops) to see if I can find an acceptable compromise vis-a-vis weight for the clean burn and the convenience of the screw top.
In summary the Vesuv cones work OK in my experience but possibly not as efficient as a cone tweaked for any individual pot/burner combination.