What's the technical difference? I'm interested in switching from Illustrator to Inkscape and would prefer to work exclusively with SVG, but is this going to be a problem for my team if they stay on Illustrator? Are .ai's more capable than SVGs or EPS?
It cannot be said that AI, PDF, SVG or EPS is more capable than any of the others. Each of these formats have their own unique boons and banes.
- Use AI or EPS when you're in a print publishing context. SVG won't make you very happy here as SVG lacks many of the features required by print.
- Use AI if you use Adobe-centric workflow. It simply works better.
- Use SVG (or fonts) if you want to do vector files for the web (as in not just using them in pixel images). Not because they are great, but because they are your only choice.
What sets AI apart of the other formats in your list is that AI is the only format that is native to an application. When you open an AI, you're guaranteed to have all features at your disposal intact. None of PDF, SVG or EPS have such guarantees. In fact, there is NO single application out there to support all their features.
Then there is SVG. SVG is by far the most ambitious of these, comparable in breadth only to PDF. In fact, nothing supports the entire SVG spec. So in all cases, saving to SVG is for all intents an export that is not guaranteed to be reversible after some other app has touched it. Certainly, if you do simple things, it does not matter; but if you need to push the envelope, you end up doing SVG edits by hand much like advanced EPS workflows.
Outside the format issues, you may find that working with other designers is often easier if you use Adobe stack. Illustrator just has better format support when it comes to working with other graphic designers. Even if you only work with web does not mean other designers that you need to share resources with do.
PDF (AI) is the modern vector graphics standard for print workflow
EPS is the legacy vector graphics standard for print workflow
SVG is the vector graphics standard for WorldWideWeb publishing.
If you only use SVG you will lose print workflow features. If you are working on a team that uses print workflow, that will be problematic.
If your whole team wants to move to a WorldWideWeb workflow, then maybe you could do that, but you would have to have a really good reason in order to make it worth it. For example, if you are only doing Web publishing and you all find the Inkscape environment to be more productive.
As for the file types, SVG is (as stated above) more of a web based file type, however you can always save as EPS or PDF, if printing is needed, using Inkscape. Also you can save and open AI files with Inkscape, and you can open and save SVG files in Illustrator. Personally I perfer to use Inkscape, and haven't had any issues. I've seen that you commented on one of the answers that you are using vector for web, so my suggestion is to go ahead and make the switch. Inkscape is optimized for web based SVG. SVG will also integrate with other applications better; if you are video editing using Kdenlive or Openshot (both Linux), you will have the ability to use SVG for titles.
I think that .ai offers more editing/creation/metadata options, but .svg can represent any graphic image. If you want to work directly with .svg, it shouldn't be a roadblock for your teammates who want to continue using Illustrator, because Illustrator can read and write .svg files without any problem.
Short answer: AI is more capable than SVG.
EPS and PDF are final, compact, one way file format. Its purpose is to be consumed as a document, either for screen or for print. It is not intended as a 'working' document. Once the EPS/PDF is generated it's not supposed to be worked upon afterwards. For example, text boxes no longer exist in a PDF, just lines of text. Sure, there are ways to open them and do minor changes in a pinch, but is not the proper way to go with them. You should always have the original native file, like an AI for example.
AI is the Adobe Illustrator native 'working' file format. It preserves all the document capabilities to work on them after you close the file. It's not intended to be consumed as a final document. They are rather large, specially if they maintain PDF compatibly or have embedded pictures. Or both. For docs with many hi res pictures, file sizes get huge pretty fast.
SVG is intended for the web, but nothing stops you from using it for print. Although I doubt it support all PDF/EPS features. SVG is intended as a final file too, but is can be used as working file. Inkscape can edit SVG files, although it doesn't has the features Adobe Illustrator has, but for a free Open Source app it's awesome.