I have never used them, but to help you get a better answer, it would help if you specified which trek you are doing, there is not just one trek and 4-5 days is the average number of days for a trek, so saying that you are doing "the four / five day trek" is really not specific enough.
My husband & I trekked with Peru Treks & Adventure this past summer. We did the 3night/4day Classic Inca Trail trek and it was absolutely fantastic! Communication with the company was good, guides were good (one of our guides Marco was super awesome!), food was delicious & all the gear they provided was clean and of good quality. I would most certainly recommend them. No complaints at all.