Here's a screen shot of TAWS colors on my Nook HD+.
As you can see, even on the vector map, which is the best case for iFly, the TAWS colors are difficult to see. I've put a red circle around some terrain near our flight path, that's not all that obvious. The TAWS colors need to be stronger and/or the overlay more opaque.
The TAWS colors are even harder to see on Sectionals, especially now that the new charts have yellow shading near mountains.
When I'm flying VFR, I always use the Sectional map. Okay, I know that, during the day, I don't really need good TAWS to avoid mountains or towers. But how about in reduced visibility VFR? Yeah, I know I shouldn't scud run. But even at 9000 hours, I sometimes do. (When I think it's safe.) And how about night? I still like the Sectional view for night VFR. I need good contrast between TAWS colors there for sure.