My simple answer is, I'm against BIP101 and all for BIP100 (as the blocks we produce say)
The pool itself (as it says in the first post) uses a size limit of 888,888 bytes
Here and CKPool solo have for a while not had issues about block sizes and spam due to our custom changes to bitcoind without using any blacklisting or targeting of any kind not already present in the bitcoind code.
bitcoind itself seems to be slowly catching up on that
I'm not open to pushing the block size down to force higher fees - especially while the reward is relatively high
(here the reward is around about 25x the fees lately - it's a statistic on the blocks page)
My issue with BIP101 is that it effectively produces a low fee environment - at the time when fees are (finally) coming more into play.
Bitcoin requires miners to confirm transactions, without that there is no bitcoin.
Miners having some control in the block size limit is quite logical and appropriate IMO
What I'm interested in the BIP100 discussion at the moment is where's BIP100?
Edit: and to put that into context: your post seems to be about pools, not miners.
Miners can choose their pool to mine at or solo mine and decide completely all transaction control for their mining.
The pool having to deal with each user mining their own random choice of transactions is not, IMO, ideal at all and also causes the problems that the now rarely if ever used GBT mining protocol has of sending way too much data (causing more stale and orphan blocks)
It also means that when a block is found by the pool, it represents the choices of a single miner that may be quite at odds with other miners.
I certainly don't ever want to see this pool mining empty blocks, and anyone who disagrees with that, I've no issue suggesting they mine somewhere else.