An update for the sake of anybody facing similar issues, I picked up a new Bosh pre-cat Lambda today and made the switch this evening in a dramatic race against the fading light.
And well, I'm pleased to report that I might have nailed it! I reset the EML and started it up with the new plug in whilst monitoring the OBD readouts that it was providing and the difference was obvious even at idle, where as previously, it was, from cold, peaking at 1.1 V top end, the new sensor was topping out at 0.7v, and seemed to be polling more frequently. I watched with baited breath to see if after a min or so it would flat line and default to open loop settings, but, much to my delight, after 5 mins of waiting for the worst it was still ticking away soundly and within the expected parameters.
Unable to contain my excitement I left the reader ticking over, and took it for a spin. Once again, the difference was instantaneously noticeable, there was absolutely no latency, hesitation or lack of power while pulling away. The next thing I tried to do was to force the turbo to judder/vent under partial load, and after 5 mins of trying I unable to do so through repeated attempts in numerous gears, this is something that I was previously able to either force or drive around with 100% success. Finally, once I was convinced she had fully warmed and I had made my way to the now empty dual carriageway, I was able to test power delivery under higher loads, where, to my delight it was both smooth and grin inducing, rather than on and off lumpy - A very noticeable increase in power. 
With this test concluded, I thought that it would be a good ideas to reset the ECU of its trimmings, so that it could re-learn with working live O2 readings. Having done so, I took it for another test run, repeating much of the above, everything was the same as before, with the exception of quick high load applications in second, where it now seemed prone to ever so slightly reeling itself in momentarily as the boost spiked. This wasn't present prior to the reset, and I'm hoping that the ECU will be able to 'learn' its way around this as it celibates itself with proper readings.
Once again, many thanks to everybody that has taken the time to share their experience or offer an alternate point of view to consider. It's soppy as hell, but without the support that this forum provides I wouldn't have the either the inspiration or confidence to problem solve half of these issues myself. 
If it's still driving like it was tonight in a weeks time I will be a VERY happy man! 
Edited by Detta, 05 June 2014 - 11:31 PM.
