We checked on Taco Bell in City Center - not anywhere near ready to open. But lots of signs up. Oddly, photos advertising tacos with FRIES!

Ah, localization.
Anyway, in our frenzied need for things chipotle-ish, we tried Topolabamba on St. Vincent Street, opposite the Pizza Anarchy place. It was really, really good! The carne asada street tacos, while made in the style, didn't actually taste like carne asada (a bit bland and with almost no grill char). But they were good. The barbacoa tacos came topped with what is actually true Texas Red - beef chunks that have been stewed in a chili mix until they were shreddy tender. The chicken onion and cheese quesadilla was excellent. (We shared.) Daughter looked like she was in heaven.
They make burritos, chimichangas, huevos rancheros, and most of the things you'd normally find in a Mex place. It's sort of a combo of Baja Mex and Tex Mex, and I have to say that what we had was as good as I've had anywhere. They have a good beer selection (Corona, etc.) and even have Horchata Ice Cream! The express lunch gets you a really good meal for about 9pounds. We got one express meal, an order of street tacos, and a bowl of ice cream (which came with two big scoops - we split it), and got out of there for about 20 pounds. (No booze, just tap water.) [And opened sinuses.]
It smells great when you walk in the door. The music is what I'd have heard in Old Town, and the service was speedy and attentive. Daughter says next time she's going to get a "naked" barbacoa burrito, which will be like getting a bowl of Texas Red, and a Jarritos (pretty much like a Mexican Coke). We didn't get any chips and salsa, as we've had too many bad salsas here. But I might give it a chance, next visit!
I hope this place lasts. Apparently they have one in Edinburgh and Aberdeen, too.