I'm not sure if using modular as an effects rack for Ableton Live is the most prudent use. There will always be that latency round-trip between your D-A, effects and then back through the A-D converters. That's not an issue in the studio as you can compensate for latency after-the-fact.
The majority of effects you'll find in Eurorack aren't dependent on sync. You might find yourself better off with a bunch of guitar pedals and an analog mixer when it comes to cost effectiveness, bang-for-buck, and so forth.