Could I recommend you take a look at this link before making your decision?
CO2: The rebreather incident
On OC I used to plan for 13 litres/min SAC rate: I'm told I should plan for 40l/min+ in case of a CO2 hit. Say you have 2.5 litres of usable capacity in your tanks at 200B; you're at 30m: you have 3.125 minutes of gas if you're breathing at 40 l/min. Theoretically you're almost OK: if you use an ascent rate of 9m/min then you're at the surface in 3.33 minutes. Unfortunately, the effects of a CO2 hit are effectively paralysis and mental confusion. Without good buddies, you're unlikely to set off for the surface immediately: in fact, the video suggests it could be quite a while. Game over.
I understand your quandrary: I travel to most of my dives by high-speed bullet train. When I go diving tomorrow, I will put quite literally 80kg of gear on my back and carry it up several sets of station steps in my journey. I wish I didn't have to carry my bailout tank, but if I die, I'm even heavier to carry.
999 times out of a thousand you're going to be OK: the bailout is for dive one thousand. As Andy Grove says "Only The Paranoid Survive"!