Hi, sounds like your Sp20 reeds are gapped too wide.
This page has a basic description about reed gaps. Googling the subject will come up with many more.
Essentially, if the gaps are high, it will take more breath force to sound a note. Some say that the Sp20 is set deliberately high because many beginners like to play hard...
I don't know about particular models being any easier to bend than others; more likely the key will make more difference, then perhaps the setup (careful gapping can help).
If you do decide to adjust gaps, remember that the reeds are easily bent out of shape so just ease them gently and take your time.
Good luck!