If you're using WebExtensions you might have to do without some of them. uBlock Origin has a version for Pale Moon, and for Tampermonkey there's Greasemonkey as an alternative. But if a particular extension is not available in an XUL version you can try searching in the add-ons site if there's an alternative that can fill in the same role as your Chrome extension, but otherwise you're probably out of luck.
Another thing missing would be some very recent JavaScript (such as regexp) and CSS features, and WebComponents. These may impact web compatibility. GitHub and Pixiv for example need WebComponents to function properly, and you have to install an extension called Palefill as a workaround. To be fair to the browser's developers, we can't really expect a small team to be able to keep up with the ever-changing web standards, especially when said standards are being pushed by Google which is known to be monopolistic. Even Firefox, which has a large team of developers paid for by Mozilla is having trouble keeping up with the new features sometimes.
On the other hand, with Pale Moon you get superior customization (complete themes are still supported which its sibling Firefox dropped, and you can even combine them with personas or lightweight themes as you can see with my screenshot from my earlier post), more powerful extensions (XUL can modify the browser much more even down to its internals, unlike the very limited WebExtensions used by Chrome and Firefox), NPAPI support (Flash, Java, and other plugins are supported and will stay supported in the far future), and less memory footprint (due to the fact that it doesn't use a multiprocess design which is notoriously resource-intensive).
Just like any other tool, it's up to you to decide which works best for you. I think the trade-offs are worth it, and therefore Pale Moon works best for me, in my opinion. If Chrome works best for you, good for you! I do use another browser temporarily sometimes if I can't workaround a problematic website in Pale Moon.