sticky in Newbies section

hey, I love this site and I have been getting great info from people here, one of the best posts I have read has been the sticky at the top of the newbies section, where it breaks down all the things you need to get started and gives web sites to buy from and people to hone blades, but there was one thing in there that I have gotten a lot of conflicting comments about.

"good hones to start out with
Norton 4000/8000 combo
Norton flattening stone (optional lapping stone for smoothing your hone, you can use 300grit wet dry sand paper and plexiglass)"

I have read and talked with other people and they have been saying that Plexiglass is not a good idea because it is flexable, and plate glass or granite or somehting like that should be used, so I thought I might bring that up in case someone felt they needed to change that in the sticky,
But, I am very new and I don't know eaither way if Plexiglass is good for this or not, just from what people have told me here.
Thanks!!
Nick