I have found that it is always worth paying a little more for quality microbore. I have seen some cheaper microbores that have started to de-laminate after just a few weeks of standard use.
The best service I have had from a roll of microbore is 5 1/2 years, it is still in working order, but I retired it last year as it had a lot of surface damage (sharp building corners etc) and I thought that i would keep it as a spare. Out of the other 5 reels we have in use the average age is about 2 1/2 years old and going strong.