With over 1 million blocks, I0coin has hit an important milestone. It shows high block counts are possible while still maintaining a stable client and block chain. I0coin is once again forging new ground in the crypto-currency world. I don't know of any other crypto which has reached 1 million blocks yet. Let us know if there are any.
I would hope so... It's damn near close to a 1:1 copy of bitcoin.
I0coin actually required modifications to its memory management to obtain such high block counts. Bitcoin has not made such changes yet, so it could very well have problems as its block count rises. GeistGeld uses I0coin's code too. So, to date only I0coin has developed the code to keep the client stable at such high block counts.
Until recently, i0coin was left for dead, it's last update having been either bitcoin 0.3 or 0.4 base.
Anyway, whatever version it was on had a severe memory leak problem that is most definitely
not present in the current build of bitcoin.