Your assessment of VL-Hot is an excellent one. It will save overhead and improve performance on older or otherwise limited systems. It works based on udev triggers. That's fine for PCMCIA cards, Express cards, firewire and USB devices, and memory cards. It most certainly does work with card readers on laptops. It works fine with both Thunar and PCManFM.
What VL-Hot does not handle are CDs, DVDs, and floppies. Inserting a CD-ROM, for example, doesn't trigger an event in udev so VL-Hot doesn't know about it. You end up having to manually mount that sort of removable media, either with something like the mount applet in Xfce or else at the command line.
Oh, and yes, VL-Hot would be a great addition to other distributions that aspire to be lightweight.