I always had a problem using just the 4x10 on stage as I couldn't hear it, the sound would just rush past my knees (and it was too heavy to take to rehearsal - I'm an old guy). Adding the 115 seems to spread the sound better.
I noticed a recommendation to tilt the 4x10 back so you could hear it better, but I don't like that solution. The 4x10 configuration is possibly the most directional of all arrays and tilting it back fires the sound out above the heads (and ears) of your audience. So while it would sound great to you, your audience would not be hearing the same sound. Tilting back works for rear-facing monitors but you will never see a pro rig with a tilted-back back-line.
The better solution is to raise it off the floor closer to your ear level. As little as 300 mm would help, 500-600 mm would be better. Stacking it with another cab as you have done, does exactly that.
Or if you want to just run the 4x10, a US$20 folding suitcase stand would rock your world.