I have a KOA T5 a custom Red Metallic T5 spruce top and a Black Standard T5 spruce top.
The spruce to my ears has a much more acoustic tone. It lends itself easier to the acoustic side. That said, the KOA and maple tops I have also played, I believe, have a fuller, rounder and a bit deeper tone. My KOA custom is really a plug and play guitar (Once you understand the T5 tone of course!). So are my spruce tops but without boosting the active tone controls on the guitars, they can sound a little "thin" depending on what you run them through. With a decent PA setup, I can plug and play and of my T5s and get good T5 tone.
The best way to use the T5 IMHO is to do the A/B box and send one side to an electric amp and one to an acoustic amp or PA (full range system). The electric side balances and rounds out the tone, filling it in, while the acoustic side brings out the higher fidelity of the T5. Sweeeeeeeeeeet!
One other reasonably inexpensive option that works well for me is to use an electric amp (Tube or SS), and run a full range speaker cabinet as an extension cabinet. I like to use the full range cab on a stand and set the amp (I use either a Mesa/Boogie Subway Rocket, Peavey Delta Blues, or Roland Cube 80x) below the cab. You can get great T5 tone in a compact package without the A/B especially if you play in cramped quarters.
To get back, (sorry if I was distracted with T5 talk), the spruce tops have a more acoustic tone in any of these setups, including straight into an electric amp. KOA is a touch brighter than maple but both are extremely well balanced. There is a definitie difference in the tone of the tops. That may be due to a thin body not contributing as much as the body does with an acoustic guitar.
There is nothing wrong either, with just running the T5 into an electric amp. It works great for solo - think of clean, clear acoustic tone free of piezo quack.
Best regards,
davidc