Sure, but the question is if the beta, 4.20, can be downgraded to 3.40.
If I "try" the regular 4.20 there is no way back. There could be an unforeseen issue with 4.00+.
3.40 can go back to any prior version.
4.00 can not go back to 3.40 (or earlier)
4.10 can not go back to 4.00 (or earlier)...