It's pretty simple for them: go and do a technical MOD2 or MOD3 dive (60m/200ft to 100m/330ft) with a Shearwater** and then compare it with the G2. Chances are if you're diving deep you'd already be using a Shearwater, certainly if on a rebreather (which nowadays is the only way you'll get that deep).Please give me more feedback on you concerns about the G2 Tek and I'll be VERY happy to deliver to the responsible party at SP HQ in EU. I have direct contact with them. They do listen to feedback as long as it is reasonable and constructive. It will be best to write it in "outline/bullet" format without being an essay type.
When you're doing your hours of decompression, consider how you'd use the information on your arms to solve various issues: bailing out, pushing deco, running higher PPO2 to reduce the TTS, keeping the CNS/POT (pulmonary ox.tox.) in check; changing the GF-hi to slow/speed up deco; changing gasses (one that's not been entered); or just looking at various parameters to relieve the boredom (SurfGF, graphs)
One would hope that it compares favourably, if not it's failed.
The big issue is if you were running a G2 as your backup "everything's died on the box including the computers" computer, how does it cope with not knowing the PPO2 that actually happened. i.e. it'll probably never be used, but mostly will not concur with your primary computer(s). The last thing you want is the thing bricking itself in a big sulk.
With the helium shortage these days, technical diving will be confined to either less than 40m/130ft ish with light deco time, or deep using CCR where the computer will need to run in standalone CCR mode so will need to assume the setpoints -- is common to run different setpoints depending on the dive.
** or Heinrich Wiencamp, maybe Ratio