Well, your first sentence is incorrect.....
Personally I like the LS1 3.5". They aren't as easy to find as the plastic ones but they plug right into the Translator without any other adaptersl AKA more places for potential problems.
Even it it's adapted to a 3" MAF pipe, the 3.5" is a major upgrade. I measured the actual flow area of both a few years ago and the LT1 was only 60something percent of a 3" pipe. The 3.5" LS1 was in the high 80's. That's a major reduction in flow restriction. And we all know that pumps work best when they're pumping, not sucking.
With only 14.7 pounds of pressure to start with every inch of pressure drop is power and efficiency that's just pissed away.