I had one in my '79 Camero many moons ago. I've seen the dash covers/mats around but I'm not sure if they are still "cool" like they were in the '80's. I only got one to cover that crack on my dash and to velcro the radar detector on it. I'm sure that the dash mat will give you some protection against the sun's rays but it all boils down to personal taste. Smooth dash or fuzzy dash. You might have to get with Starsky and Hutch on this issue.
This isn't going to answer your question about what the dash cover blocks or doesn't block. Just wanted to say that IMHO, I think dash covers are definitely uncool. I can understand if the dash is cracked or flawed somehow, then you may want to cover it. Some people may also want to cover it to prevent the dash from cracking ... but I doubt that modern dashboards still crack like they used to in the 70's and 80's. My '94 Accord bakes in the Texas sun every summer and the dash shows no sign of cracking. For what it's worth, I'd suggest using sun shades and avoid those uncool dash covers. =)
I recommend http://www.dashhugger.com/
I like theirs because, unlike some, it comes down further on the passenger side,,, even covering the area around the passenger's air vent. The air-bag area is covered, but it's cut like a flap & won't impeded air-bag deployment. It is cut out for all the air vents, but does cover the dash tweeters... which I like. It doesn't impede or block the sound from the tweeters & I feel will give them some protection... seems like a live & harsh place for speakers... up against the glass in intense sun/heat.
Since you are in Los Angeles, I'd stay away from the Velour dash covers and go with the carpet ones. The Velour ones really look nice, but the rubber backing on the Velour ones will start sun-rotting & will disintegrate in a couple years... I had a Velour one originally on our Accord & won't do that again.
The Ody is supposed to have a non-reflective dash, but the first thing you'll notice is the reduced glare after putting your cover on. I live in desert, and they are an absolute must out here. Another thing I like about Dashhugger, is that they use velcro that won't melt or deteriorate in high heat.
Call up and ask for color samples, since you have the GG... I'd ask for the Light Green, Dark Green, Smoke, & perhaps the Teal color samples. They recommended the smoke for my SS, but I got the blue colored samples along with the Smoke. I went with the Crystal Blue as it is a great contrast with the SS and puts some color in the interior... and I just didn't like the Smoke as it was a bit shiny which is the last thing I wanted in the desert.
If you go for it, it'll come in one piece rolled-up in a box. The best thing to do is lay it out on your dash, then pull your Ody out into the sun & park it a couple of days & let the sun & heat relax it to your dash. Then install it. All the velcro connections are already sewn into the cover, all along the front edge. You just take the other connecting velcro pieces and attach them accordingly, then see where that hits the dash, swab that spot with the little cloth they send you, then peel off the paper back and press it down... repeat accross the front (I think it was about 12 spots) and you're done.
Just be sure you have it lined up where you want it before your start. Note the cut-out for your VIN number when lining it up.
2001 Starlight Silver LX
Keyless Remote Entry & Alarm
Trans. Oil Cooler
Crystal Blue Dashhugger
Falcon Lumbar-Comfort Cushions