Thanks for the info.Erm, its handy to check things like pre boil gravity and post boil gravity - as a couple of drops on the glass cools to room temp almost instantly.
But as my head still works in normal hydrometer scale - i have to use the online calculator to convert it! Also its not as accurate as a hydrometer. i can normally read it accurately enough to show a difference from say 1.050 and 1.052 - but that level of accuracy isnt possible on the brix scale in my hydrometer.
Its a gadget. Not a useless gadget, but not essential!
Being one to over-obsess about the numbers I'm prone to running round in a mad panic to cool a sample and check BG with my hydrometer - and if necessary recalculate hop additions to hit a specific IBU number! (yeah, I know it's stupid!) And do all this before my wort comes to the boil/boils over
And then in the end the boil-off and/or OG is different anyway or doesn't tally somehow.
So yeah, I can see how being able to take a reading much quicker would be handy. Or I could just chill out and stop worrying about the numbers