DC300 Dude, you will hit the Sterling 4i much farther than 210. You hit longer than I do, and I can hit the 5i 210+. Have you hit the Sterling low irons? They're AWESOME.
Everyone is different, but the Sterling 7i is my 175-180 club with a relaxed swing. The 6 is around 195 relaxed, easy 200 if I'm motivated. The lofts are stronger than most variable length sets, so it's hard to compare directly, but I hit the Sterling 5i better than I used to hit my VL 4irons on good shots. Longer, more accurate.
I've hit the 4i off the tee when really going after it distances so silly I don't want to type them here. Stupid long.
I don't have experience with the Pinhawks. I can tell you that if you have some swing speed you will nuke the Sterling low irons.