I built the same, a copy of Cushcraft Ringo Ranger II (two 5/8 wavelength collinear array + ground plane below feedpoint) for 6 m myself about 20 years ago. I modeled its electrical performance using MININEC 3.13. Wrote it up in CQ magazine.
Major problem was mechancial stability & strength. A strong wind would cause QSB as antenna bending whipped the major lobe up & down from the horizon. It worked excellently on 52.525 but I roger the potential lightning problems. I also built one for 29.6. Talk about mechanical nightmare. I had to guy it in the middle using Dacron rope but it too did a nice job on 10m FM. The next time I want vertically-polarized gain, I think I'll go the copper plumbing or aluminum route using folded dipole elements + coax cable balun/Z transformer inside the hollow element. ****** BTW, my hearty thanks to all who take the time to give detailed answers to tough questions on this list. I am learning! --John WB0EQ