The 'guru' of crankbait fishing from NC (David Fritts) recommends the slower ratio reels. I bought one of his combo outfits some years ago (slow retrieve reel and fiberglass rod) and simply love it for crankbait fishing. I found that I had marketedly better success with that setup.
Getting crankbaits to their proper depth does not depend near as much on 'speed' as it does crankbait design and type/size of line. But, then again - different strokes for different folks.
Lot's of factors to consider.
Here's a review of the Bass Pro Fritts Cranking reel - note the gear ratio:
"I have this reel in the 4.7:1 model and i put 10lb berkely100% flurocarbon. then i matched it up with a st. croix mojo bass crankin model. i can cast a dd22 five country miles, or a bandit 100 two country miles(i hope you know thats an exaggeration) the slow speed really triggers strikes, i think that is because i see guys throwin crankbaits with a 6.3 or 7.1 reel ratio. i only use 5.1 or lower with a crankbait, so buy it and make sure that when you spool it you have a lot of free time if you buy the 4.7:1 gear ratio."
My two cents. I agree with the comments above. When I changed to the Fritts combo, it made a great difference in crankbait fishing.
Tex