You could easily do that project in both, but it may be easier in some sense to use DB Pro because it does not limit you, but it may be easier to do it in Classic because there's not as much to learn. I was programming with Blitz (argh! cough...hack, wheeze...dying, dead) before and for my birthday my parents got me DB Classic and the book (3d gm too, but don't get that). We're finishing up (starting really, blitz never got us anywhere) our first person shooter in DB Classic, then if we sell enough copies of that we're investing in a copy of DB Pro to take advantage of all the features.
It really depends on how much you want to spend. Definitely get the book, but you may want to just get DB Pro so you don't have to upgrade later, and yet people who have Pro every once in a while still make something in Classic for the heck of it.
The fact that DBPro has more features doesn't necessarily mean the games you make will always be better than those made in Classic, check out
http://www.starwraith.com, most of those were made in Classic. This post is not really going anywhere, so go ahead and ask some specific questions, and we'll be all too happy to answer them.
Crazy Donut Productions
Current Project: KillZone