Had some time to scan thru some videos looking for the weight of a 701/0(10Car Unit)
Probably some meaningless data but hey at least it shows a 10car 701 is 26% lighter than an 8 Car Class 450.
Used this video(Credits to him) and with several hundred button mashing's of the K key managed to get some data off the in between carriage Vehicle Data label:
Total Weight Of 701/0 = 347.0 t
Total Length Of 701/0 = 203.11 m
Width = 2.77 m
10 Car Train (34.7 Tons Per Average A Car)
Vs
Total Weight Of 450/0 = 351.42 t
Total Length Of 450/0 = 163.2 m
Width = 2.796 m
8 Car Train (43.9275 Tons Per Average A Car)
Class 450 Is 26% More Heavier On Average