I just did a bunch of research on this (for my 2003 LB7), and literally just received my pump yesterday. Planning to install it this weekend.
I bought a Kennedy twin pump "everything" kit, which includes the wiring harness, fittings, hose, and billet pickup (not sure if it's needed, but the pickup
is REALLY small on an LB7). In my research, I never heard of anyone having any low fuel level issues, or being starved for fuel with this setup.
For an extra ~$50, I also ordered a Napa 4770 filter head, Baldwin BF1212 filter, and a couple of mini ball valves to isolate the additional filter (for easier changes).
I'm basically going for this setup, except twin pumps and only one filter head:
https://www.duramaxforum.com/forum/diy-tech-discussion/806281-my-lift-pump-kit.html
I had a hard time finding any disadvantage to this setup. The pumps are extremely quiet, have extremely long typical life spans (measured in the 10s of thousands of hours, several decades for most people), flow-thru design, and two pumps are proven to make 1000+ horsepower.
And with the Baldwin BF1212 being drawn thru as a primary filter / water separator, and something like a Baldwin BF46062 (4 micron rating at 99.85% efficiency) up front on the OEM filter head as a secondary, I think that's gonna be about as good as it gets as far as filtration goes. And cheap, too.
The only drawback I can possibly think of is that the pumps aren't self priming. But with how easy it is to prime them (basically run the truck, and then turn them on), this was a complete non-issue to me.
Just my opinion. YMMV.