Have you replaced fuel PUMP? at what miles?
 

I am very big on preventive maintenance - I would much rather replace a part on MY time, in MY driveway then on the cars time on the road or pay for a tow.

Curious if and what miles your fuel pump failed.
ALSO, did you change out the whole plastic sender unit as I was thinking to do just the elec. pump part.
AND, does anyone know the original manufacture of the elec. pump?

My X has never left me stranded, (except a flat tire) and want to keep it that way.
Read that running the gas tank low shortens the life of the pump (full tank keeps it cool). I drive from full until the gas light goes on and @ 160+ plus miles.

I never had to replace one on either of my BMW's. I just follow these rules:

Not running too low on fuel tank
Replacing filter periodically
Always trying to pick top tier gas at newer gas stations and watching for inspections stickers

I'd say if you use real oem and than go to Pelican Parts or few other good places, it'll tell you different manufacturers and which one is OEM. On something like that I'd probably go with genuine BMW.

It was replaced twice by the previous owner.i have all the paperwork.Both times, he was really low on gas...bottom line, change the filter if you haven't and don't run on low fuel.

What was the milage at replacement?
Yes, I have replaced filter, twice. My low gas bulb will probably burn out - I hate getting gas.

Mine went around 112k miles. I was getting symptoms like when I was at a red light my rpm would fall so low it would almost cut off and then 1 day it did and didn't turn back on

I changed mine out after 200000km, it was an easy fix, left me stranded in another country, (Wa state) but i was able to walk back to Canada (i live 5 blocks from the USA border in Lynden Wa) grab my trusty Jeep, picked up a new one (ouch!!) and grabbed some tools, and off i went. My dead giveaway was no whirring sound on start up, and cyl 1 misfire with fuel cut off codes. checked fuses, and its def a fuel pump! changed it out in about 10 min, trickiest part was getting the back seat to stay up when i was pulling out the pump! at least my fuel tank was pretty low (light was on) so the pump wasnt dripping with fuel all over my seats, none the less, i put a few clean rags down to catch any potential fuel drips!
it was a pretty simple re and re, just an inopportune time and location of the breakdown! i wont run my X5 down to empty anymore! when the light comes on, i take it as my call to get fuel at the next exit!

it failed on me at 95,000kms
most likely due to clogged filter because the new one sounded kinda funny, than I changed the filter the next day and it sounded much quieter and smoother

Mine went out around 140,000 miles.

And did anyone just change the pump part, or everyone replaced the whole sender/pump unit?

The entire unit is easy to change, just the pump, it's marginally tougher and perhaps the plastic bits might be a bit brittle! If it's not rediculously more I would opt for an entire unit!