16 Days ago SHIELD announced a private testnet based on Bitcoin Core 0.16 was running.

This was a move to get away from the original forked Verge code and all the glitches that continued to happen. This post was also before the latest 51% attack on Verge where hackers mined $1.9 million worth of XVG in a matter of hours based on faulty code.

On May 24, SHIELD released their official announcement for Shield 3.0, explaining that XSH would update to Bitcoin Core 0.16 by block #800,000, with examples of what the upgrade will deliver for users and performance enhancements.

https://medium.com/@SHIELDcurrency/shield-3-0-a2c3ea27d485

It is fast. SHIELD 3.0 will start up faster, sync faster, and just feel faster. Though SHIELD’s code was originally forked from Verge’s outdated codebase, the new SHIELD 3.0 has been completely revamped and is now based on the latest version of Bitcoin’s time-tested and actively maintained code: version 0.16.

This not only closes old vulnerabilities and adds new optimizations, but gives a clean, stable checkpoint for development on SHIELD Core going forward. For example, the Verge code seems to be a codefork of Peercoin, and their patching out of Peercoin’s proof-of-stake (among other things) has led to many scattered code leftovers that are difficult to work with. Though adapting SHIELD to the new codebase was indeed tough, it will pay off in spades; future core development is now made more efficient, thanks to the well-documented and publicly-scrutinized Bitcoin code.

Reference:
https://shieldx.sh/
https://www.investfeed.com/article/114994/shield-30/
https://www.reddit.com/r/SHIELDCOIN/comments/8inkpn/bitcoin_016_testnet/
https://www.coinexchange.io/market/XSH/BTC