Steem is highly inflationary, SP isn't.
In fact, SP is a significantly inflationary as well. The inflation rate for SP is something around 10% - which is similar to Bitcoin's average inflation.
What might matter is that Bitcoin's inflation gradually decreases, whereas SP's inflation is meant to stay at 10%. That's why I suggest we consider changing this a bit in order to make SP more similar to Bitcoin.
RE: Should we establish a long-term cap for Steem supply?