As stated above, you have about the same chance of water for either. When a sump is setup, you build in all of your redundant fail safes. For instance, return placement can greatly impact the reverse siphon of a power loss, or you can do what others do and have a small hole drilled to break siphon. My return is placed so that I have very little water above the top of mine in this situation. So, if power fails, between my tank still draining and the reverse siphon, I don't even 3/4 fill up my return chamber of my sump and the rest of the tank is the same, hits about 55% capacity AFTER my drain off from the DT after a power failure.
Also as previously mentioned, depending on the return flow you are wanting, a return pump is going to run close to the same wattage as a canister filter(s) would. So, for instance, on my sump I am running a Fluval SP4 @ 0 head is 1822 GPH and has a max wattage of 88W. A Fluval FX6 runs at 564GPH @ 43watts. So with 2 FX6, you have just over 1100GPH @ 86W and a significant increase of money spent to reach 60% of the capacity of a single pump.
The fluval SP4 is a more expensive example, as stated earlier cheaper pumps can be purchased. I have had good luck with Fluval and chose this pump after extensive research and knowing that I am gone quite often, I felt more comfortable with a more recognized brand than a knockoff. Strictly personal opinion.
Also with this setup, I have nothing in the tank but 2 siliconed overflows and a digital thermo probe that blends in with the back of the tank. All heaters are in the sump, no return pipes that are hanging down the back wall, so intake tubes, etc. Frankly, I hate having the thermo probe in the main tank, but the amount of flow I push through my sump has proven to give inaccurate readings when the probe is in the sump. This make be different for others, but I felt like I was fighting a never ending heater war cause it was always 2 degrees cooler than desired, I got curious and moved it to the main tank and wouldn't you know the temp was perfect again. But I digress.
Ultimately, you should go with what you are comfortable doing. If you will leave the house panicking about returning to a flooded home, then maybe the sump isn't the best option for you!