Hi Nickgreenberg, Lugia and Ronin1973,
Nickgreenberg: I am using a few effects pedals, in combination with a digital mixer it's great to use and almost no limitations that come right to mind of using them in combination with modular. The only limitation I see here is the limited number of outputs on your mixer because you don't only need inputs for those pedals (that will be the outputs from the pedals), you also need outputs on your mixer for your pedals (that will be the inputs for the pedals then). Ideal to get this configured with a digital mixer that can do digital patching as well. The PreSonus StudioLive Series III mixers for example can do that just fine.
Lugia and Ronin1973: If I may be honest here, and you know how much I love (Eurorack) modular synthesizers, so it's definitely not a lack on my side of not liking modular, however if it comes to effects versus Eurorack modules then I am not overly impressed. Especially when you calculate the usually ridiculous module price into it, as Ronin also already indicated, then for most effect modules I don't think it's really worth it and an external pedal might be preferred, or at least I prefer than an external pedal.
The Intellijel Springray2 is one of the very few exceptions for me where I say, yes that effect is really worth it within modular. Perhaps the Make Noise Mimeophon as well but that's about it, and I do have a few more effect modules but I am not even going to mention them here. They aren't bad but no big wow factors, especially not for the money one is paying for it. I rather spend my money on a (very) good (stereo) pedal. Of course Ronin's pointer of the CV control would be the only real good reason for me to get an effects module in modular, but wow, what must that module be good before I would decide to go that road... Good news is that slowly pedals start to have CV input(s) as well, so for effects... please think twice before you get an effects module instead of a pedal.
Just my 2 cents, kind regards, Garfield.