DBC is cheaper and an old product TGC developed, it's in their past and you can't expect them, whilst they're dedicating their time to their main products to make everything work across old products (do you expect MS to still support Windows 98 or Apple to support MacOS 9? Or Maxon to still support Cinema 4D 7?), DBC was great when I used it and DBC users as far as I can see manage just fine without the extra features and support DBP gets, bearing in mind DBP is more expensive, thus users are going to get the better stuff, but look at Starwraith, Evachron and Soul Hunter, they're all sexy looking, well made products that didn't need any of these extra tools, if you really need them, upgrade, if you can't afford it, make do.
Out of the plugins you get for DBP, I'm only using Sparky's DLL (which works with DBC), a D3D dll because DBP's text slows down the FPS too much and Evolved's shaders (which you can't expect DBC to support because its built on an older version of DirectX). All of the fancy TGC released functions are just a convenience, and one I'm not paying money for unless I have the spare cash for them. Sparky's is just fine for collision and I don't need DarkPhysics, I don't need Dark AI because I can code my own AI and well, if you want to buy the extra modules, as Jeku rightly says you still need to pay money for them, so instead of buying those, buy DBP and grab the free user-made alternatives to the plugins. (instead of DP download Newton, instead of Unity, download Barnski's LUA plugin for example)
