I can't find any technical information that backs up his claims ~ which leads me to believe he is just talking out his ass.
HFS+ only journals meta-data. Journaling support was retrofitted into HFS+ via a simple VFS journaling layer in XNU that?s actually filesystem independent. The journal files on an HFS+ volume are called .journal and .journal_info_block (type jrnl and creator code hfs+). HFS+, although not a cutting-edge filesystem, supports some unique features and has worked well for Apple.
Just compare this crap to ext4. And about case sensitivity:
Although often believed to be case sensitive, HFS Plus normally is not. The typical default installation is case-preserving only. From Mac OS 10.3 on the command newfs_hfs -s will create a case-sensitive new file system. HFS Plus version 5 optionally supports case-sensitivity. However, since case-sensitivity is fundamentally different from case-insensitivity, a new signature was required so existing HFS Plus utilities would not see case-sensitivity as a file system error that needed to be corrected. Since the new signature is 'HX', it is often believed this is a new filesystem instead of a simply an upgraded version of HFS Plus.