since i started tec diving, i can comfortably say, this was the most debatable topic i had with multiple tec divers with different level of expertise's. my tec instructor uses AI and a redundent SPG. however when he goes below 90 meters he only trust SPG and removes AI as it is an addtional failure point "in his view". personaly i am more of an AI and tending to remove SPG as i had a good number of SPG failures over the years (not a fair comparison, as i used SPG for much longer). currently i am planning to remove the SPG and relying on AI only on my main reg and deco as well. these days i belive that AI has been long enough to gain reliability. and i love the fact that it calculates SAC, view all air supplies on my computer and later i can review the data and understand more my breathing patterns. so as an answer it depens on your risk assessment on either or both.