Hi Reet,
I've been using TW encryption for years and it's been very reliable. I use a single-file TW for everything (currently 5.2 MB) with approx. 2k tiddlers. I'm not sure how encryption works when you use one of the other access methods (bob/node.js etc.)
I reckon it will add some overhead on startup: once you've provided your password and hit enter you'll wait longer until your TW is decrypted and loaded the larger it is and the slower your device. But for me encryption has been a critical feature since I use the single file for everything and this additional wait time is well worth it.
You might also be interested in this discussion on this group:
If you're concerned about data corruption, probably the single best measure against data loss is to make frequent backups. But again, I would never expect it to happen because of encryption.
BTW, there's also a plugin allowing you to encrypt single tiddlers only, though I don't personally use that.
I hope this helps.
Enjoy!
Hubert