BBB speed as "USB controller", not mass storage

dear BBB experts—let’s say that I want to use my BBB’s client USB port for a USB gadget device, but not as a USB mass storage device. think

char buf[16];
while (1) {
fread(buf, 16, 1, fusbin);
for (int i=1; i<16, ++i) buf[i]=buf[i]+buf[i-1]; // real-life, most stuff here.
fwrite(buf, 16, 1, fusbout);

16-bit byte blocks are probably too small for USB block transfers.

USB 2 should have throughput of about 480MBps best-case. Can the USB gadget device in single-byte mode reliably hit 1/1MBps (or about 100/100KByte/sec upstream downstream)? or am I limited to the old 115200 baud rate, which is only about 1/10 of this speed. Any experiences?