You realize that Deathscythe has it's own shield correct? You're basically ditching a launcher shield for a custom made buster shield from a different gundam that'd you are also presumably fan dangling a beam whip into as well so keeping the buster rifle in there is also a big question. Also where do you keep your buster rifle or beam scythe when you're not using the other weapon exactly?

This is Deathscythe Hell when it's back is folded up. It's POSSIBLE you may be able to put it on the back via a rack but it'd be a heck of a way to lose your weapon in the middle of a fire fight and keeping it in there is another thing. Plus even if you have a method to keep it on there with some sort of closed rack or whatever be it then you'd need to open it in the middle of a fight making it unreliable. 

[img]http://vignette2.wikia.nocookie.net/gundam/images/0/08/XXXG-01D2_Gundam_Deathscythe_Hell_Back_View_Lineart.jpg/revision/latest?cb=20101205094034[/img]

This is Deathscythe with it's wings open. It's even worse.

[img]http://vignette3.wikia.nocookie.net/gundam/images/f/fc/Gunthumb2_lg_H.jpg/revision/latest?cb=20140106144416[/img]

Also the weapon is as big as Wing Zero's leg

[img]http://4.bp.blogspot.com/-NIiRfhbE0qo/UpLvRyGC_vI/AAAAAAAFcso/_Cn7vGbJNd8/s1600/3a5.jpg[/img]