I think you could still float the top link even with the check valve (I guess the proper term is pilot valve) cylinder, if your loader valve and 3rd SCV is the same as my 4310, my 3rd scv lever has a float position, not sure if it has a detente lock like on the loader stick though?
If it's true that most of the leak down occurs at the cylinder then probably more reason for the pilot valve. As sometimes you might not have/want the HTL connected to the remotes, if you needed them for something else. prevents you from having to switch back over to your manual top link, as it stays in a locked solid position.
The one negative about the pilot set up is you can't drop or other wise move the cylinder with out engine running. So if you turn off machine and want to lower under gravity, the position of an implement you can't until you restart. Not a biggie but it has happened to me more than once.
What I found was only pilot valve HTL was easy to find and order regardless of my preference, So I got it and have no regrets.
Good Luck,