well the guitar i entered this month for the contest is a hollow body and it is made out of walnut back and mahogany top, the sustain is a little less than a solid but not by much, also it is completely hollow, it doesnt have a feedback problem at all and i play through a mesa!
in my opinion i say go for the chambers! it will lighten u the guitar a little and i dont think it will take away much of the sustain if any, if you do it the same as in that picture. as for the neck angle, what i did was i drew a straight line on some paper, then added the angle line, 4 deg. is what mine are(you can do what you wish) making a point with both lines, then i use this as a template for a few peices of wood 3/4 x 12" long and i cut them to the same angle, mount them to a template of the neck pocket and you will be able to get your neck angle when you route.
just make sure youi line up the template right when you place it on the body, so that it goes to the right depth you need. also its easier if you do it before you glue the top on!
good luck and i hope this helps!
also i was using the www.fullservesite.com for my pic hosting but i cant figur out how to do it anymore? im stupid! lol