I'd suggest a high speed comparator with all the -in's brought to one VREF (driven from a DAC), or for cheapness, a bunch of LVDS receivers instead of comparators. The main difference is, you'll be able to find comparators with wide input voltage ranges, but LVDS probably not beyond 5V. There might be 5V LVDS chips out there, but they'll be slower (probably not 150 meg), and still that's only 5V, not even enough to include ECL and 5V CMOS or more.
You could further add limiting/protection circuitry, that could extend the operating range, potentially at the cost of additional loading (e.g., current limiting resistors pulling on the circuit) or speed (series resistors, additional capacitance, protection diodes, etc.).
Tim