Well, the T1 is discontinued so you're looking at the $600 T4S vs the $330 Zed mixer. Both would use the analog output as the L1 Compacts don't have a Tonematch input. Both would handle two singers and two guitars fine with the available 4 XLR inputs and at least one stereo channel. Both have EQ and effects, but the Tonematch's are more advanced, plus you can save scenes on the Tonematch. Either would do what you want at minimum, so you have to sit down and compare the rest of their features and see if the Tonematch's additional features justify spending another $270 on the Tonematch or if the Zed would fill your needs.
We have a dual L1 Compact setup that I feed with a Soundcraft Signature 12 MTK, supporting 4 vocals, cajon and acoustic guitar through a TC Electronics G-Natural (plus a Bluetooth receiver for break music) and it does fine for us. Plus it has full multitrack recording capability over USB vice just stereo (and does that as well). For me, I didn't much care about digital mixing and scenes without a dedicated sound guy (we control from stage), as the more things I have to change between songs, the more dead time there is between songs. But, you may have a need to use multiple scenes during your set, so you have to decide that for yourself.
Hope this helps,