I use a pull saw with a high teeth count, but effectively use it as a push saw. Kindof like how sometimes running things in reverse has a better effect. It will "bite" less and you can get some pretty good lines and go through it fairly quickly.
I've gone through a couple of iterations on the polycarb tops. I don't find that they block too much light, IMO unless you are running a low-powered light or have a super deep tank, the tops aren't going to block too much light to cause issues with plants. I run them on all my tanks including a 55 and it's fine with plant growth.
There are a couple of annoyances with them, though. The twin-wall construction will collect gunk AND WATER in the channels, which will make for a mess if you aren't careful picking it up and letting it drain before accidentally doing so all over yourself. I used gorilla glue waterproof patch and seal tap in order to keep water out of the channels, and it works well, albeit a bit messy looking and a pain to cut given how sticky and thick it is (but it works well).
The other issue is how to make an opening for feeding. Picking up the whole lid is annoying to feed. I've made them by cutting an opening and using the same tape to create a sort of hinge, it works aright but not great.
I'm working on another iteration of the polycarb lids now. I've gotten some end cap material to use instead of tape, and I managed to snag some hinge material from the local plastics store to help make a nicer opening for feeding. To do any sort of gluing with this material you'll need to use acrylic cement instead of super glue.
All in all, they are a good choice if you have a need to make a lot of lids since you end up buying a long 8' sheet of it at once, but there are probably cheaper and just as good if not better options if you only need a couple of them, glass being the obvious choice.