Judging from the structure of the game's info page, the collection is its own item, coming with its own installer. It's not just a bundle of four separate DRM-free items. So its possible that it has DRM management which the individual games don't have. I'm actually downloading it at the moment, so I can probably give more reliable information later.
Please do. I am interested in Sega Bass Fishing. The others would be alright I guess. I still have my Dreamcast and a copy of Crazy Taxi laying around here somewhere.
I downloaded and installed the compilation now. The compilation is indeed one item. You even have to install all four games (they are listed as seperate in the game's installer, but I saw no way of deselecting anything). The compilation uses Starforce DRM, you need to be online for activation, and the key is limited to 3 activations (GamersGate will supply you with new keys if you run out of activations, but it's still very restricting and inconvenient).
I looked for a way to install/play the games without using the activation, but didn't find one. GamersGate downloads four separate cab files, one for each of the games. You can extract these manually, but they are missing the executables. These are contained in the compilation's installer. Afterwards, even if you start a game's executable manually (i.e. without using the launcher that's provided for the compilation), it will ask for a serial key. If you're mainly interested in SEGA Bass Fishing, and don't want to encumber your machine with Starforce DRM, then you're probably better off buying that game separately. The separate game is denoted as "DRM Free" in the shop.