I used to play standing up (pizzicato, jazz), until one of my teachers suggested me a chair, especially for practising my bowing and technique in general. now I practice with this one exclusively and bring it to longer gigs as well.
as far as sturdy/light-weight ratio goes, I guess this is as good as it gets, the chair was obviously designed and produced to last, the warranty is 5 years!
there are models with (faux?) leather seat, but I went with this one, I preffer for the seat to "breathe". the seat's cover material appears to be tough, and the foam underneath returns to original shape immediately.
the height for both the seat and leg rest can be set perfectly. the seat can also be set at a different angle, but I only use that feature when folding the chair. you can further minimize the folded size by lowering the seat, but I find it not necessary.
if you have a car, it is a no-brainer to take it to a gig; as for the public transport - it's not too heavy, but if you already carry a double bass... it can be a handfull ;)
all in all: 10/10