This might be helpful.  
 
http://www.bikesmithdesign.com/Short_Cranks/

Joe, I bought my first 150 mm crankset from Bikesmith Design (Machine my own in my home shop, now). Mark Stonich does really nice work.
 
If you want to use a double-ring, GPX crankset, Bikesmith shortens SRAM Apex 10-speed cranksets. I have one of those installed on my 11-speed ICE VTX. Nice crankset that works with 11-speed chains, should you want to convert your 10-speed bike to 11-speed in the future. I ordered a cyclocross crankset (46T/36T chainrings), machined the arms to 150 mm, and replaced the 36T ring with a 34T. In a 46T/11T gear combination, theoretical speed at a 100 rpm cadence is 32 mph. The VTX weighs 33 lbs 8 oz, ready-to-ride. I can climb my steep test hill OK in the trike's 34T/32T gear combination. I also have a 150 mm cyclocross crankset installed on my 27 lb 2 oz, 11-speed Metaphysic high racer, and can climb that same hill OK in the bike's 34T/28T gear combination. You might want to consider using a 50T/34T crankset, instead of a 53T/39T, to make it easier on your knees, because you will be applying greater forces to the pedals with shorter crank arms. Lower gearing will lessen these forces.
 
Hope short cranks work for you. I suffered with knee problems for years, until I installed 150 mm cranksets on my recumbents and set the booms so the angles of my knees were not less than 90 degrees at the beginning of the power strokes.

Joe, the Bikesmith website has some crank length selection guidelines for riders with and without knee range-of-motion problems. Using the no range-of-motion problem guideline, I should be using 160 mm cranks. Probably wouldn't work for me, as 165 mm cranks hurt my knees. I plugged my numbers into the "Crank Length Calculator" on the Recumbents.com site, resulting in a 135 mm crank length recommendation for a 90 degree knee angle. Big difference. I just guessed when I selected a 150 mm length. Luckily, it worked for me. 155 mm might have worked, and would have provided a little more leverage.
 
I ride the 46T ring most of the time, including when I climb short hills. About the only time I ride the 34T ring is when I encounter a steep, long hill. Don't have any problem transitioning from the big ring to the small ring. When I do, I don't spin crazily, I just slowly turn the crank and rapidly upshift the chain on the cassette. I'm not strong enough to spin out the 46T ring on the flats in the smallest cassette cog (363 watt max short term output). When I spin out on long downhills, I just coast the rest of the way to the bottom.
 
Regarding your "high BB" vs. "medium BB" question - I would think your CA 2.0 would have a high BB and a Cruzbike Silvio a medium BB.
 
Reference your ceramic BB comment - Several years ago, I read a test report for wattage loss of a number of ceramic and steel bottom brackets. Seems the bearing type was not significant, as far as wattage loss was concerned. It was the seals and lubricant that had the most effect on wattage loss, with the tightest seals and most dense lubricants causing the most loss. I installed Omni Racer ceramic bearings on three of my recumbents. On two of them, the ceramic bearing BB-equipped cranks spun more freely than when they were equipped with steel bearing BBs. A MegaExo, steel bearing BB-equipped crank on my Metaphysic bike spun more freely than when the crank was equipped with a ceramic bearing BB.