Blend/mix controls

Zoolooter

Do I need a blend control, is it that important? I'm aware that it controls the wet/dry balance, but if you blind tested would you hear a difference?. I ask because a can pickup an old Holy Grail reverb (without blend) pretty cheap used. With blend it's twice the price.

Teetonetal

Depends on how the original is set. Personally I like reverbs to be either very subtle or in you face 90% wet. To get between the 2 mix/blend required.

english_bob

On a reverb pedal? I rarely use the one on mine- just set it at 12 o'clock so it's roughly 50% wet. 

Agree with @Teetonetal though, it does allow you to do way more- mostly/fully wet reverb sounds are good fun and you'd also be able to get long reverbs that don't overpower your signal, which a simple "moar reverb" knob won't necessarily allow.

Although of course it also depends on what you're using reverb for. If you're thinking more Dick Dale than Jonsi Birgisson then it probably won't matter so much.