If it helps: we're running several 10-15TB filesystems with ReiserFS and never had even the slightest problem with it. The current limit, however, is 16TB even for ext4. Or, to be more precise: the filesystem could handle more than 16TB easily, however the tools necessary to create the filesystem (aka mkfs.ext4) have a hard-coded 32-bit limit that's been detected almost three years ago and has still not been fixed. Which should not affect your 2.7TB partition tho ;)
Martin