"The larger the blocksize, the more there is to download with a full client is installed... so having an excessively large blocksize will drastically increase the amount of data needed to be downloaded and stored."

I thought with an increased block size, more transactions could be fit into one block. So for the same number of transactions, whether the block size is 1MB or 400MB, the blockchain sizes would be kind of comparable, yeah? From my understanding of what I just read here the blockchain gets significantly bigger only when there are enough transactions to fill up a ton of blocks. ie a blockchain with 400MB blocks is 400x as large as a blockchain with 1MB blocks only if the transactions/second are 400x that of the blockchain with 1MB blocks so that the 400MB blocks are filled at the same rate as the 1MB blocks. If there are the same number of transactions per unit of time on both blockchains, their size is roughly equal because the size of each transaction isn't very different (if at all). So in the case where the rate of transactions is equal, there would be far larger blocks on the 400MB size limit chain but far fewer blocks.