same set-up here. Only the noise of the harddisk, an IBM Ultrastar 2.1GB which replaced the original 52MB Quantum is drowned by the noise of the MSTE's fan.
I dont own a Cosmosex (yet..perhaps) but the external cased Ultrasatandisk I've got works fine. I wouldn't use an internal one because of the inaccessibility if you want to change cards which I do a lot. Internal is cheaper but needs modifying the Atari's case if you want to change cards easily.
(Strange thing is, I never could find a clear picture of any Mega ST or -STE with an internal US disk inside).
Downloaded Atari software like Cubase modules, drummaps, sysex files for hardware synth's, editors etc, are stored on a Atari/DOS formatted SD card in the PC's card reader first and then inserted into the Ultrasatandisk. With the driver I use I can transmit 32 MB form PC to ST in one go which is the same amount of data as an old and noisy fully loaded megafile 30 holds.
What scares me most is putting the Cosmosex into the MSTE or any Atari for that matter. You need to put it where the "A"floppy drive sits so you'll lose that one which is not very convenient especilaly if you don't have an external "B"floppy drive.
Modify the housing, loop flatcables through the back of the MSTE to reach the acsi port, making "weird" connections to hang an USB keyboard onto. It's all to much for me.
For Cubase and editors my advice would be, purchase an Ultrasatandisk. Swap SD cards for exchanging data with another set up on another Atari* (simple STf/m or something, they come real cheap nowadays. Sometimes people give them away for free because they don't want to throw them in the bin) with a second US or even a Cosmosex for real time editing synths and making back ups, an awful lot of memory storage. You'll never use it all.
*Also handy is to obtain a so called PARCP cable and SW from Petr Stehlik if you want to transfer data between two Atari's with harddisks or SD card drives like Ultrasatan connected to them or data transfer from PC to Atari through the parallel port (also with USB available now).
And for my USB optical mouse I bought a little gadget on Ebay. Fantastic! Fast as lightning. Should actually being slowed down instead of speeded up.
And then the Internet. Atari's are far to slow afaic to surf the net. I leave that to the PC.
Have a look:viewtopic.php?f=103&t=26999http://info-coach.fr/atari/documents/_m ... _Guide.pdf