If I may inquire which machine is this for?
A 128K or 512K requires a machine that can support 800K disks. You can write a 400K disk on a machine that has an OS that doesn't speak 400K MFS at all.
A 128Ke, 512Ke, Plus, Plus ED, 512Ke ED, II, SE with dual 800Ks or 800K + HDD will require a machine with a 800K drive. Only a Macintosh with an internal drive (or compatible external, aka Duo, 2400c, a few other PowerBooks) and that can boot into OS 9 or earlier can support this operation. While there may be some esoteric options for PCs out there, the reality is that barring exotic hardware, there is zero support for 800K or 400Ks on the PC platform and zero support via USB FDDs because the 400Ks and 800Ks use GCR encoding, not MFM like the PC world. They also use variable speed drives, instead of fixed speed drives like the 720K and 1440K PC drives.
USB floppy drives will support HFS if the host system can read it (i.e. OS X, some (all?) Linux distros). Or, HFS Explorer...sort of. PCs can write HFS 1.44MB disk images if they are of the type supported by the imaging application, like NDIF.