They offer sheet sizes up to 24" x 48" for prices comparable to what I can find from Laird Plastics locally (they don't carry .040 or .080 often). Shipping is free for orders over $125. It cuts well and vacuforms well.
For strip styrene I got a lot of it from Hobbylinc.com a while ago since I needed other stuff from there at the time. I'm not exactly sure how their prices match up. I've been using that for quite a while, or scrap from other stuff I've cut.
I've noticed that, as well. Different formula and/or processing of hte plastics, I guess. The Plastruct plastic is a bit harder to cut and shape, overall, but I prefer it whenever I'm scratchbuilding a structure. Plus, the Plastruct plastics seem to hold hard details better, whereas the Evergreen tends to be a bit softer. Both have good and bad points is all I'm sayin' and it depends on my needs as to which I'll purchase.
For me it's all about availability. Plastruct is simply the easiest way to get plastics if you live in a rural area. I have to drive several hours to get Evergreen. Plastruct is always a click away. $8.00 shipping, but it's fast.
I agree about the softness, as well. I'm quite used to Plastuct - so Evergreen has an "Oops" factor for me.