The 16x08 does have 16 inputs, but only 8 mic preamps. If the OP needs to record more than 8 mics, you can do that easily with 2 US-16x08 boxes. You connect one via USB to your DAW and leave the other with no USB connection. It will then default to an 8-mic preamp, with inputs 1-8 connected directly to line outs 1-8. Those line outs can then be patched to the USB-connected interface's line inputs (9-16). Easy peasy.
Go to the Tascam US-16x08 Getting Started page and scroll to the bottom to check out this blog post.
Introduction of US-16x08 in the Home Studio of Masayuki Muraishi
Product: US-16x08 | TASCAM
And if you haven't noticed, Tascam have posted the v2.0 driver for the US-NxN line. The US-16-08 and US-20x20 drivers pick up a new Mixer Driver feature that uses WDM. While not ASIO multiclient, you can connect your DAW via low latency ASIO, and connect Windows audio to the higher latency Mixing driver (10.x mS latency vs. 16.x mS for me for one specific measured route; still tolerable, since I use the Mixing driver only when I want Windows audio played through my Tascam i/f, to, for example, play a Groove3 video while I have SONAR open).