People get ingrown hairs with carts, disposables, SE, DE, SR. YMMV, I was lucky enough to switch to DE which gives me no ingrown hairs or irritation(unless i shave very fast and recklessly). I think the flaw in my case of the carts is that they get TOO close, since they have to pull the hair under the skin to cut it. If you are lucky enough to not get any ingrown hairs from carts then it's definitely more effective than a DE also the "carts are too expensive" argument is kinda not true anymore. Many companies have surfaced over the years providing cheap carts. YMMV as always.