Using Astroimager on my mac for a quick test, the camera set to an exposure of 60sec. Once the exposure has finished it's just seating there at 'downloading image' for ever and ever and ever...

First I would use a powered hub (5V separate power into the hub) as the electronics for the Titan run off the USB- only the cooler works off the 12V.

That's what I already run

To the best of my knowledge if you get LIBUSB_ERROR_TIMEOUT you're having problems with powering the camera.
I was facing the same problem in the past until I powered the CCD correctly (CCD connected to USB hub, Raspberry Pi powered from the same USB hub).
Since then all the problems are gone.

I will post the test over the weekend. Now I'm in the middle of the session so cannot do this.
Just do this to test the CCD:
1. install the drivers on your PC
2. connect your CCD locally to your PC
3. run indi_ccd_test locally
4. check the results

If the test is successful (and I bet it will be) your're facing the powering problem i.e. the CCD is reset somewhere in the middle of the test due to powering problem.
I assume that you're connecting the CCD to raspberry pi.
Additional thing that is usefull is adding max_usb_current=1 to your /boot/config.txt - this will set your USB power to the maximum supported by the device. This made my life easier and my Atik Titan works correctly even without active USB hub.

Thanks for the help, I do not run a Raspberry PI but an Odroid C1 and a powered USB board.
I'm currently in Germany at my observatory site, I'll take this damn Titan back home in the UK with me over the week-end and run some tests from home.

Are you running through any extended cables or chain of hubs? USB over Ethernet doesn't play well with the Titan.

I can tell you one thing. I wouldn't exchange this CCD to any other It really depends how you use it because it's not perfect for everything, but still it is very good CCD.

my setup is:
Odroid C1 --> Yepkit USB Switchable Hub (with a 5v3A power supply) ..> USB cable --> Titan

I know it's a good one, I had it working on my old (very old) Windows XP laptop.....

How do you power your Odroid? Separate power supply or from USB hub?
I was facing some problems while powering RPi from separate power supply, including closed loop problems which generated bizzare artefacts on the CCD when powering from separate source. All of these problems are gone since I power my RPi from the USB hub. This takes one of the USB ports but it's worth doing this anyway.

The odroid has it's own power supply.
Well, I have a monster of a power supply, it's a 12V one with lots of amp (can't remember the spec) and I have some 12v to 5v converters.

Judging by the randomness it could be a timing issue. If the drivers are expecting a certain timing based on a particular host or a particular setup in terms of hub etc it could be the reason for a timeout.

One thing I don't like about libusb is it's habit (code wise) of combining error codes so you don't know why thing have happened..If the download took longer or some how got mangled then it's likely to cause a problem.

The sad thing is I can visualise the original driver source.. and my rewrite that formed part of AOSX many moons ago. I can help guide/troubleshoot but I can't go into details about the drivers.