hi gray my tank is acrylic and is 8ft x 3ft x 2.5ft and as yourself i had the dilemma of choosing between the 2.i'll go through the points that made me choose acrylic over glass.
1.my tank is constructed out of 25mm thick acrylic and weighs 52% lighter than the glass equivalent and it still took seven of us to carry it in to my house.
2.guarantee - with a glass tank ask about a warranty most companies will laugh at you.i had three quotes off very well respected companies and all 3 said they could not guarantee the tank.with acrylic the tank is melded together and is very rare for these melds to break and was confidently told that this tank would last 50 years and more.
3.clarity is by far much better than any glass tank that i have viewed.
4.far easier to work with than glass e.g drilling holes.
5.although it does scratch relatively easy at least with acrylic it can be buffed out. try doing that with glass.
6.insulator - my tank has no heaters at all now with only the lights doing the heating and only fluctuates by half a degree over night,i had 3 x 300w heaters in my last tank,saved me money on the leccy bill.
the company that built my tank was image plastics in birmingham and the owners name is paul,this is their website
http://www.acrylicfa...et/page008.html,
it was not cheap and they were the 3rd company i phoned.the first company i spoke to was the acrylic aquarium company which turned around and said that they would not take the job on because it was not in their financial interests to do so,who would say no to 4 grandsworth of business, so i would really stay away from these.the second company i spoke to was talking plastics who did not even have the decency to phone me back after i enquired.
paul at image plastics will bend over backwards for you and is a genuinely nice guy phone him before anyone else you would not be dissappointed.
well i hope i convinced you of your purchase
regards
jason