You definately want to use 601 with the 501 as it helps the cleaning and durability. I use a wool pad with everything on gelcoat. This time I changed it up a bit and used 601/501 with a wool pad and then topped with 601/105 with a white foam pad with a DA. My last ventiure was 652 then 601/105 all with a wool pad. A few washings with 932 and a few applications of Aqua Wax and a few applications of 932 mixed as a QD lasted a little over 1 year with minor oxidation. Sure beat the usual 3 month oxidation when using other products.
Dave