We have used both methods. Dolly was great when we had an older Camry that could not be towed 4 down without a lube pump (not worth the expense). After a few years we bought a CRV and sold the dolly. Fitted the CRV with a towbar, brake system and wired in the tail/brake lights to include a charge wire. Costs for each were very similar. Maybe only $500-600 more for the four down setup on a $2000-3000 setup. Dolly was a pain to store and we avoided many parks that we otherwise had enjoyed. Now...good used dollies with brakes can be found at bargain prices. But if you are handy (I'm not) four down systems can be found on Craig's List, eBay etc. as well. Just my $.02.