Heavily personal preference... but some considerations:
Weight ALONE is not the primary point. WHERE is the weight, and HOW does the DISPLACEMENT play a role?
The thousand has greater reciprocating mass WITHIN the motor, and THIS is part of what makes it "feel" heavier. (Less prone to LEAN as readily... more prone to STAND up in a turn, etc...) On a STRAIGHT or MOSTLY STRAIGHT road, there is LITTLE if ANY notable difference in dead weight between the two, BUT... the thou will reward at MUCH LOWER rider input relative "grunt" and "thrust". (You don't have to push it as hard.)
What TYPE of roads do YOU ride? WHERE do you ride? (Mountainous region? OHIO?)
If you live in an area where EVEN on the 750, you don't get into higher gears much or you tend to do a LOT of cornering, especially TIGHT corners, you may PREFER the way you can exercise the motor with less "risk" relative throttle control, and focus more heavily on the HANDLING pleasures of your ride. Where the 1000 requires MORE if not nearly ALL (at times) of your energy (focus/mind) to be spent on THROTTLE CONTROL!
As some will say... there is NO replacement for DISPLACEMENT...
...on the OTHER hand... the only replacement for TORQUE is HANDLING...
It's all about where and how you ride... not so much "which bike is better".
'03 R 1K w/Yosh Cams 0.45mm mhg stiff springs Ti retainer/keepers Ti Yosh full system w/CF can PwrCmndr Kevlar lines Ferodo Race pads/ '86 1255cc Frankengixer/ '86 RG500 etc...