I had to do some chores around the engine today as I took the car out of winter hibernation. I wouldn't want ANY reduction in engine access. For me it's an 03 or 04 top or live with the plastic.

Just installed a retrofit top:

Acoustic fabric:
I just installed the autotopsdirect top with the acoustic fabric. Compared to the oem top, the material is thicker and made for a DRASTIC improvement in wind noise. I highly recommend the acoustic material.

Autotopsdirect vs. GAHH
Autotopsdirect and GAHH sell the same top, which is actually manufactured by Sierra auto tops. The only difference I know of is that GAHH offers a lifetime warranty on the glass and autotopsdirect is 3 or 4 years (I forget which). Considering the 400+ price difference, I went with autotopsdirect. The odds of the glass debonding over 3 or 4 years from now while I still own the car seem to outweigh spending an extra 60% for an extended warranty.

Visibility
Visibility hasn't been a problem for me - if you're shorter it won't be a problem at all, for taller people you might not be able to see cars more than 50 feet behind you without moving your head. I'm about 5'11" and dip my head from time to time to change the mirror angle. Nothing drastic - I would take that any day over chopping the plastic when putting the top down or seeing swirly headlights behind me. Aesthetically, the car just looks cleaner overall with a glass window.

Engine Access:
This is my biggest concern with the top. The pictures posted here pretty much explain it. I would clean the MAF and do simple maintenance like that without a problem, but anything more serious and I'd be looking for ways to get better access. The glass bumps the roll bar when you try to lift the rear of the top, so perhaps unbolting or removing the roll bar when doing serious engine work would be an option. I'll cross that bridge when I get to it...

Tieniber, yes ! That's the one... autotopsdirect. Thanks for the feedback. coincidentally, I'm also 5ft 11"... and I sit with the seat all the way down... Hmmm, looks like autotopsdirect it will be.

Tonycarreon, it's a 4 bow frame and it was a 03 (l looked at the chassis no...). But the top was really new looking, hence not sure if it was an aftermarket or original top.