my cage started life as an Autopower bolt in and i had visions of wanting to remove some day at first. and i did not have any welding skills or friends with them, etc.
i have since added door bars and some welding of the sleeves to the cage while leaving the bolts in place.
my ITB crx si has ~ 150#'s of ballast in it and moving 5-15 #'s of bolts and sleeves down to the floor beside me has not been a high priority.
but if starting from scratch, i would weld the cage in and not bother with the sleeves and bolts. a bolt-in cage is essentially a welded cage that was assembled and then cut in strategic places and then sold with sleeves to allow it to be re-assembled in the car.
the headache with trying to do a retro on my cage now is that i no longer have good access to some points that need to be welded. there are various threads around about how to assemble a cage and how/when to move it to get access to the welds.
for instance, cut 2" holes in the floor to "drop" the main hoop through the floor to tip back the hoop and allow the A-pillar hoops and hoop above the windshield to be welded 360° around with more ease, etc.
good luck regardless of which path you pick.