The "performance" increase is only important as far as the 200 series devices' ability to support some additional features and expanded capacity (e.g. supporting four different service providers vs. two for the 100 series). The "performance" of the 100 series is already sufficient for VoIP telephone calling.
The current 200 series ATAs do not have a jack to connect the devices to the PSTN (POTS, or plain old telephone service). If you aren't using that function today (e.g. not bridging VoIP calls with land line or other service provider calls via that jack), then you won't lose any functionality by upgrading.
If your 110 devices already work fine today, and you don't need the extra features of the 200 series, then there is no reason to upgrade. If one of your 110s goes bad, then that would be the time to get a 202.
Obihai is updating their website. Here is the new link to their product information page:
https://www.obitalk.com/info/products