Verbfactor would be an awesome idea! It would need massive hall reverb with full wet mix – my idea of heaven! I play with a cello bow on occasion and having reverb like that sounds awesome! Maybe the inclusion of a fender twin type reverb and a warm plate reverb would be nice. A tails option (reverb continues to a natural decay when the effect is turned off rather than a sudden halt) that switches into true bypass when the reverb has finished decaying would be awesome – digitech hardwire reverb has a tails option but that means that the signal is buffered continuously meaning no true bypass at all.