YES join the no magic crusade!.......on wait, you have warlocks.....boo, your out!
OK serious time. Looks like a fairly solid list with a tone of shooting that will be hard to take points off. You then have some fast units to pick up small points here and there, and the smashtastic block. Personally I wouldnt feel safe with only one proper threat unit.....it only takes a good hit with a doom rocket/treb/firey convocation etc etc etc to wreck the whole block (unless Hellebron brings a big magic resistance) and then you have lots of things that deal damage, but not much to actually wipe units out.
Theres no actual magic resistance on the Executioner block.... however, and spells that target it miscast on any double, and I have +6 to attempts to dispel them (lvl2 warlocks +4 for hellebron item). Trebs, Mortars, Hellcannons can definitely demolish the unit, but I think its pretty capable of wiping out most things in combat, even with only 5 or 6 models left.
Another thing, Chariots/Pegasus/Dark Riders/Warlocks all put up a pretty good amount of hurt in combat on their own. As long as Im using them to finish off things, not grind down whole blocks, theyre more than capable in combat.
I think i would REALLY struggle with some kind of blasted standard warrior deathstar with double hellcannon backup... but I think this list just laughs at the standard daemon prince double crusher style warrior lists.