Finally decided to get with the program and bought clipless shoes and pedals. I'm 68 and been riding since I was about 6 or so and have used clips & straps in the distant past. Bought the Shimano A530 pedals just in case I wanted to ride without the clipless shoes. Got two pairs of pedals, one for the DF and one for the recumbent.

So far I've ridden the DF and should be able to get out on the recumbent this afternoon (I hope).

Anyway, I've installed the cleats in the forward position on my shoes which are pretty much in line with the balls of my feet. Riding on the DF was pretty good with the possible exception of some minor ache on the top of my foot near the ankle. Not sure if this is from being able to pull up on the pedal (not being used to doing this lately or just new shoes).

My question is, on the recumbent should I set the cleat back to the second position on the shoe so that I have more of a flat foot on the pedal stroke or leave it forward where there might be a possibility of pointing my foot forward? The difference between the forward and back cleat attachment locations is 10 mm.

Are you seriously considering changing cleat position every time that you change bikes? I'd leave well enough alone unless you identify some problem.

No. I was just wondering if I should change the position to the rear, if it would be more efficient. Would use the same cleat position for each bike. Sorry that was not clear in my question.

Update
Well, that was embarrassing. Thought I had unclipped at a stop sign and immediately fell over on my left elbow. Lucky that I was on the recumbent with less height to fall and had a sweat band and a couple of velcro straps to staunch the blood. Worse part is broke my mirror and had to go home to clean up the wound.

Gonna have to keep some first aid stuff in the bag now!

I have my spd-style cleats all the way back in my Shimano shoes (mtn). Works for me - my riding is 100% recumbent.

I've gone down twice in recent years while riding 'bent. Both unrelated to pedals/clipless and both times onto left side with left elbow gashes. Seems to be a trend.
Carrying first aid stuff since the first one.

I did ride just a bit longer after I fell over and it seems that I might put the cleats on the back mounts and give them a try there. Also going to practice getting out of the pedal on the up side (leg bent rather than extended like I did when I was riding my DF). Seems to be harder to unclip with my leg extended.

The wife could not believe that I fell over riding the recumbent.

Have put together a kit with large bandaids, gauze pads, tape and ointment. Going to make up another one so that I have one for each bike.

Edit - went out this morning to check on the spring tension. Found out that the left pedal was set quite a bit higher than the right. Corrected same.

I put a powertap on my recumbent to find out where the most power for me was produced with the least amount stress on my legs. I found I produced more power, 40+ watts more, with the cleats in the forward position on my shoes.

It's not just power production, it's protecting your Achilles tendon. The farther forward you place the cleats, the more stress on the tendon. Listen to your body and if there's any pain, be prepared to move it back pronto!

I'm going to replace the 51 cleats with the 56 cleats as soon as it stops raining here in Houston. Hopefully the 56s will allow me to unclip easier and in more directions than the 51s.

I'll pass on what the fitter who did my bike fit said. When he evaluated my cleat position which I set myself, he said I had them perfect for the "old position" practice, which was at the ball of the foot. He indicated the newer school is they should be back from the ball slightly. Having said that he indicated since I was not having any pain or other issues, he suggested leaving the cleats where I had them.

Finally was able to get a test ride of about 9 miles yesterday (planned for 20 but got rained out again!).

Got the 56 style cleats and installed them on the aft cleat position. Felt good and was able to unclip very easily. Cleats stayed in position without a problem. Only problem seems to be with my left foot, some pressure on the outside of my foot in the pedal region. May have to make some adjustment there.