and boom go your six flames if GDI does not entirely exist of super-nOOObs because on a good team
a) you get warned early ("2 flames right, 2 left, etc. or "enemy spotted!")
b) hottys lay mines around the agt so that the flames are on 10\% health when they are coming nearer and will then be blasted by infantry from the back.

Done this so many times, GDI defending mostly wins by points just defending rush after rush.

GDI===BOOM there goes the obelisk

BOOM and BOINK will go your engies!
again, not very likely to succeed against a pro-team, where the ob is mined inside out.
better to try reaching the MCT of one of the other buildings first, that are more likely to be unmined