Keep testnet as close as possible to the live system. It will sort itself out in a few weeks.
Create an additional block chain for those whose development needs require something other than what testnet provides.
Create an additional block chain for those whose development needs require something other than what testnet provides.
No, it won't sort itself out "after a few weeks". Let me see if I can do a back-of-the-envelope:
Difficulty on testnet currently at 373. We want it no higher than, oh, 5, so with the typical 3-or-4 machines CPU-hashing on testnet generate a block in a reasonable amount of time.
So we generate 2016 blocks over 8 weeks. That cuts difficulty by four: ~90
Then do it again: ~22
and again... ~5 SIX MONTHS later
That's optimistically assuming we can find people to cooperate to contribute hashing power to generate 2016 blocks at difficulty 300 in 8 weeks or less.
If you'd like to continue using the old testnet chain, be my guest.
I'm sympathetic to the "testnet and main net should have the same rules", but the truth is the testnet has, and always will have, many fewer people hashing on it.
Changing the main net downard-difficulty-adjustment code might make sense, but that's the topic for another thread. Allowing main net difficulty to adjust all the way from 22,000 to 1 isn't the right answer (it makes sybil attacks where an attacker feeds you a bogus version of the block chain much easier).