The item that mostly worries me from the proposal is that it doesn't address quadratic validation time.
Solution is pretty trivial:
To prevent worsening block verification time because of the O(N^2) hashing
problem, the simple restriction that transactions cannot be larger than 1Mb
has been kept. Therefore the worse-case of block verification time has only
doubled.
Yes, and in fact, transactions of 1 MB are ridiculous, because they could easily be replaced by a tree structure of smaller transactions, changing the N^2 into N log N.
All the arguments against "bigger blocks" are bogus. Non-mining nodes have nothing to do with decentralization (of power), and the N^2 time has to do with the size of individual transactions, which have been erroneously left to be much much too big from the initial design. There is simply no point in having such big single transactions.