We had a Doyle lazy jack system with Stackpac. When it self destructed we switched to a Mackpac system. Our boat didn't have the right mainsail for any lazy jack system. I can only respond to what was wrong with it.

Our lazy jack problems.

Out main was a too heavy cruising main at 12 oz and just wouldn't flake or fall between the lines without hanging up. Also, our partial battens (at the leach) would easily hang up on the upper line and I always had to watch it as it was being raised sometimes lowering the main a foot to uncatch it. We didn't have 'full battens'. You need full battens for lazy jacks.

I put the highest line on each side of the mast about 1/3 between the spreaders and the mast head (where suggested). Too high. It didn't need to be that high. I had always thought that if I put it lower, on the spreaders about a foot out it would have been much better.

I should have taken the time to work out a good stowing system at the mast while sailing. It was always a chore to stow the lines and they really need to be stowed. It's ugly and un seaman like if you don't stow them

With our problems I discovered that when it was time to raise the main I'd stow what was the leeward lines first. The main wouldn't hang up on anything as there was nothing to hang up on. Stowing the leeward lines before raising was incredibly easier.

i never liked the lazy jacks but it was better than not having them. If you're ordering a more normal weight main with full battens most problems should be a non issue.