SVG implementations on browsers have historically been poor, though this is certainly improving. You'll hit many bugs and unsupported features. IE The worst problem may be SVG itself - SVG 1.2 which dates from 2004 was abandoned, and most browsers implement SVG 1.1 which is rather lacking in features. This makes it hard if you're a designer to produce SVG documents which a browser can actually render. At a bare minim…
You don't need to sanitize SVGs to host them safely - you just put them inside tag and browsers will do sandboxing for you.
What features do you actually miss in SVG 1.1? Gradient meshes? 3d transforms? multiple fills? I can think of only advanced stuff that is rarely used and tricky to do with other web technologies anyway.
Also, why would you want to strip browser-incompatible SVG elements? Browsers will simply ignore such elements.