Their pads take up only about 1/3 the tub space, my beardies love them and often sleep all night on them, but also regularly sleep in the cool unheated area under their fake rock ledge.
It's their choice, and having access to a nice toasty heat pad helps them digest their 2nd live insect (crickets) meal of the day (they are only juvis and need feeding 2x per day).
I'll soon be testing some 35W dichrotic halogen lamps and imported fully ceramic RS-GU10 adapters, 50W is too hot for my tubs . If these give an acceptable temperature at the UV basking spot I'll use these during the day along with the existing heat pads and 13W UV10A10B CFBs over winter.
They'll be in full size individual enclosures in spring with MVBs.