Like others, I have midships rail cleats on my E34-2. They work fine for springlines (which I definitely use at the dock, as it is often an upwinds, and less often a downwind slip, so midships springlines lines have better angle. (I am too lazy to run springlines all the way to the bow/stern...) The cleats are fine for that, but I would not use them for major loads (like an anchor or something -- I'm sure the rail is strong, but why risk damaging the track? So I have wanted "true" midships cleats... but never *needed* them for anything.
And like
@vanilladuck and
@bgary , I use a cheek-line (did not know that was what it was called) to pin my boat at the dock when returning singlehanded. Cleats were always fine for that -- I actually rigged a lasso-line though the cleat, dropped the lasso over the dock key-end cleat coming in, then used the primary winch (letting the line slip on it) to slowly brake the boat. Then put the line through the self-tailer, and engage motor forward (with helm over) to pin against dock. Again, no problems, but also not super-high loads. [Or I did this, until I felt comfortable enough with reversing to stop. Now I coast into the slip, reverse to stop, and jump off and cleat on the spring line. Single slip, so no worry that boat is not pinned. Insanely easier and less stressful, but if the engine dies I'll be (somewhat - I coast in slow) sorry...]
I wouldn't hesitate to tie up a dinghy there, though I would not tow from a midships cleat for obvious reasons. For rafting up, I'd make sure any larger loads were being taken by the big bow/stern cleats, or a fore/aft springline to the midships. I'm sure that rail is very strong along its axis, but pulled perpendicular to the axis I'd rather avoid, even though it's probably still very robust.
But I would NEVER drill through the deck in that midships area to install a more robust cleat, for the following reasons:
1. The chainplates are near there, and boy would they be expensive to fix. My E34 (a later build by Pacific Seacraft) has cabin-internal tie-rods that grasp other fittings going through the deck. The most common way those all go bad is water leakage causing corrosion, and then the fix is extremely expensive as those rods are no longer made, so custom metalwork to high specs. So why introduce new leak opportunities?
2. The headliners on these boats are old. If you damage them (read: the zipper goes) it will be hard to ever get it looking right again. So why go in if you don't really need to?
Plus, a big cleat clear of the rail there will bite your foot occasionally (but painfully) when you go forward along the side, and tangle jib sheets when that is least convenient (i.e., in higher wind when they are flogging. The smaller rail-cleats have never done either to me.)
I'll look at the brand on my cleats; they have a clean side and a locking side (where the horn slopes in to help lock the line.) Some may like this, some may not... it's not what I might have chosen, but is working fine for me even with two (fore & aft) springlines attached, albeit 3/8 or 1/2" lines when I do that.