Janab, i have driven both the bikes. I find no such problem with the delux disc brake, actually i think you are just not using the brake right.
Honda and Suzuki are two different companies.
Honda is good in fitting and Suzuki is good in sitting. I think you will have an idea from that.
Suzuki's disc brake containing bikes are much more suffisticatedly adjuted and assembled than Honda. They are assembeled here, but the parts are more compatible in Suzuki.
On the other hand, when you drive HOnda 125 delux or CG, the first feeling you got is "hard, stiff, rough" type, and in Suzuki, you feel first time, as comfortable as you are sitting on a Sofa, (i am talking about GS 150-125), that is the real difference i feel.
The brakes are excellent in CG 125 Delux. You might have not had a good experience on that i think so.