I just thought of another reason why a surge tank is a great idea..
With in-tank EFI pumps, you have to keep them submerged in gasoline or they will overheat and fail, requiring replacement.. They are NOT cheap...
This happened to me twice on my 2001 Chevy express G1500 (currently sitting up on blocks for over 2 years now because I simply could not afford the $3000 to replace the catalytic converters).. as a result, I always kept at least 1/3rd of the tank full (anything under 1/4 tank is tempting fate, especially in the summer months).. This essentially reduces the true capacity of EFI equipped fuel tanks by 25%...
But with a surge tank, you can use the full volume of the tank.. The pump in the surge tank will always be submersed, and even more so than the in-tank kind..
Even if you ran out of gas in the main tank, you'd only be exposing the surge tank pump to an unprotected condition for a few miles and as such the risk of destroying it would be much less than the same condition with an in-tank pump... 10-15 miles, vs 60-90 miles or more... a few minutes in potentially damaging circumstances vs an hour or two...
Just something else to consider... This is also true of a frame rail mounted pump vs an in-tank model...
FI pumps are not cheap.... It hurts when they fail... Not to mention that replacing them is much more of a pain in the ass with an in-tank style pump...