dolly vs flat

I totally agree the 4 down is much easier and convenient to connect and disconnect, but with the people I personally know the troubles and money involved I will stick with my dolly, no troubles in over 6 years, one friend bar failed twice under warranty and the second time dammaged the front of his 60k trick, another the brake control has repeatedly failed causing expensive repairs to the unit to be required. My initial investment cost me 700, both of theirs was about 2k the first time and then all the repairs. But they still swear by their tow bars four down.