should I switch out AEtherling , Melek, Izzet Paragon , and 2x Hound of Griselbrand for Guttersnipe , Invisible Stalker , and 2x Markov Blademaster ?

this switch would lower my average cmc. then I could probably switch the 2x Izzet Cluestone for some instant removal or maybe counters?

i think i figured out how the sideboard should work. Is there any matchup I might have forgotten?

I have since removed the 2x Nightbird's Clutches from the sideboard (I never used them) and bought 2x AEtherling to fill its slot. Should improve my deck against creature removal. I wasn't mana hurt very often, so I only bought 2 steam vents to replace an island and a mountain. I was playing with only izzet gates and basic lands. I should really invest in sulfur falls before they phase out to get some use out of them to replace the slow izzet gates.