I wouldn't be too afraid of the convertible. Top back glass delamination is the only significant issue. Can't be successfully repaired (reglued) due to the high fabric tension and replacements run $3-4k, which should be a budgeted long term wear-out item every 15 years anyway. Fortunately for buyers it's hard to hide and easy to see from the outside of the car and in pictures.
Otherwise the convertibles are just as solid as the coupes, plus they have and extra 1/2" thick steel channel in the lower rockers and a big steel x-brace underneath. Al's team designed the entire 6th gen chassis for ZL1 torque in the convertible first, and there were/are no stiffness downgrades based on drivetrain, so SS/LT1/V6/T4 and coupes all benefit. This is part of the reason why the coupes performs so well on road courses, they're much stiffer than the GM cost accountants would want it to be. There is zero cowl shake in these cars, the high doors keep the interiors pretty quiet even at highway speed with the top down, and the downward tilt of the infotainment display eliminates all sky glare.
If you go with an 8 speed, just plan/budget to flush the transmission fluid every 50kmi and shudder likely won't ever be a problem. Or tune out the TC slip, or both.
The 6th gen is a significant step up from the 5th in most respects. You won't be disappointed.
