I love wyches, and here there's a lot of people witch have to switch Kabal for Wyches, in last months.Yes, I'm talking about competitve games.
Wyches simply give you what Kabals never do: they are a 4++ with legs. There's some lists that simply you cannot stop it with fire, so you need something to block enemy units in CC for 1 game turn.
Wyches are the way for.
Yes, first apperance isn't so good, but after thinking and thinking, we found Wyches extremely usefull for this purpouse! They aren't designed to make damage, they will die. But, they can stop guys like Wraithknights, Dreadgnoughts, wounded units, single models, elite units (like Terminators, Centurions, Obliterators etc).
They even do damage at Pink Horrors, Cultist, other small objective units etc.
Yes, you can do this with other units....with other MORE EXPENSIVE units!
In a normal DE army Wytches doesn't fit...but, in a extremely MSU army, they are perfect! I have play a lot of games with MSU DE army with Kabal, but Kabals cannot give me much things other other shoot. I needed somtehing blocking in CC, not all the enemy, just some units, to shoot down others.
Fighting the enemy pice by pice.
For 50 points (65 with Heka haywire), you have an extremely usefull stopper unit (of course designed for elite units, not 50 blobs IG..) AND keeping at least 5 shots with pistols. I prefer sacrifice Kabal shots, for some protection/aggressive CC.
They can stop a lot of elite units (think about assault single unit with more Wyches units if you need. I play 4×5 units and against bigger units I can simply launch 1-2 units in CC, to make the deal), giving you a better fire concentrations;
They can clean up some objective from small units, so you don't need to spent 2-3 Venoms against 10 pink horrors getting ground (for example).
In a MSU firing army, I found Wyches extremely usefull, and worth.