Am i a fan of http://www.lumobodytech.com/ ?
Hmm, I need to think about this.
The proposition seems logical. A system that “knows” when you are holding  a static “correct posture”and holds you to it.
I think my only reservation is the idea that there is a correct  static posture. Certainly you need a stiff core, but your position when seated,  is best often  changed  ( see some of the observations by McGill).
But, if it  reduced your slouching by  say  15 minutes a day , and encouraged you to learn a bit more about your posture, and improved your general back hygiene,  the £80 seems totally worth it.
But, It could fall into the Standing desk error. There are very few safe static postures!  if you work at a desk, rotate between kneeling, sitting, sitting side on, standing ,holding a lunge.
I suspect , having tested a similar system ( the computer’s camera kept your head in a frame) that its  possible to get a “good reading” in as much as you haven’t “tipped” the sensor, but, you have  actually collapsed your back.
Ill try and test that out with this product.

Support your back  
Less of this
 
more of this
  
Employing a lunge strategy and transfering load to your legs by the use of arm support is highly validated to be good for back health. Think about your day to day  back hygiene 

You make or break your back in your day to day movement . You either have good or bad back hygiene

The big warning.
Some back pain is really serious: check your RED FLAGS by clicking here 

do not over look the connection between sleep , stress and back pain . If you get too tired , you stop paying attention to your form. Stess has to express itself too