Nothing wrong with leveling a gx. It's just not super op like I was pre-renewal. I just 150d my gx grinding my ass off and doing the turn ins solo or with a small party (usually with no healers) and using zero bottles of EDP. This includes dragons, scarab hole, bio2 and ash vacuum. Only skills used were rolling cutter+meteor assault+cross ripper slash, ctrl-click crits+weapon block/counter slash and backslide. Playing a Sinx prerenewal required some skill to be good, almost no skill to be ok. Playing gx right now actually requires some level of skill to be effective.
The only thing gxs lack are the super op skills some other classes have, but I think they're quite balanced as it is. Don't be a quitter and just learn to be effective with what you have. It's like saying you don't want a gf cause you dont have a big black d....
while this holds true they do lack variations in MVPing compared to the other class counterparts it'd be nice if gx's had leech end re-enabled on mvps but on a more watered down scale