Yeah, the weight DIFFERENCE is not that big a deal.
The front ARB and Shrock are about the same weight (ARB doesn't MAKE a rear bumper though).
You remove the stock bumper and mounting brackets, lower fascia, etc...so adding the real bumpers is only adding the difference between them....say an extra 65 lb or so (~40 lb oem stuff comes off).
If you put ~ 65 lb on your front end to simulate the effect, you'll SEE the difference is negligible.
If you ALSO add a winch, that can add ~ another 100 lb all by itself though, which doesn't so much sag you, as add cantilevered weight forward of the front tires, as far as impact on your suspension.
As 2000 - 2004 X's have built-in front height adjustment, you can crank the front end back up if you need to compensate for any sag anyway.
Its built-in because t-bars sag with time all by themselves...so Nissan put t-bar adjusters in from the factory to help compensate.
If adding a winch, bumpers, skid plates, sliders, and so forth, up grading the t-bars to stronger ones does help fight sag, and adds some suspension stiffness to handle the extra weight.
:wink-big: