Well, I got my Safariland.
I went into Leed’s in Oregon City (www.leedway.com) and asked about the Safarilands.
Didn’t want to pay as much for the full drop-leg ALS holster, and he didn’t have any non ALS for my 1911 in stock. So, he got out a “used” 6004, hood-only holster. A local PD dropped them into him, because the ambi-saftey on their Kimbers didn’t fit in the holster. So used, but basically new, holster. He sold me the holster piece for 20 dollars, and opened up the package from the ALS holster, and sold me just the thigh rig, for 85 dollars.
So I ended up with a basically new 6004 holster, on a quick-release buckle leg rig, mounted and out the door for 99.99. 
First thoughts; It’s very sturdy. I haven’t decided if it’s more or less comfortable than my Serpa. I definitely see the advantage of Blackhawks dual-belt-loop system. However, the Safariland is less complicated. No adjusting for different style pants (Belt loop placement), what I might be wearing under my uniform (Underarmor, regular boxers, nothing at all…), or even if I just need to shift it forward while in a vehicle.
The thigh platform itself is much lower profile. I can sit without the rig resting uncomfortably on the seat. However, the holster itself is very robust, and sits away from my leg a great distance. So far, it appears to only be from my first-person visual angle. I haven’t bumped it on any doors or anything, yet. But the single thick strap to the belt is very stiff, and made it uncomfortable to low-crawl across a field across the street. Not impossible, but I definitely had to fight the holster.
Now, onto a tossup. Inside the holster, there is a suede “lining”. I assume this is not only to protect the finish on my gun, but to hold it steadier too. It succeeds in both. But, I don’t mind about the finish on my gun (Good tools are used tools.), and I think the retention would be fine without it. However, the gun is not going ANYWHERE unless I remove it myself. I think, even if I left the hood down, the gun would not flip out of the holster.
This lining also makes for a noticeably slower draw. Trying to pull the gun straight out, it’s almost “locked in”. If I rest just my fingers on the front-strap of the gun, I can NOT pull it out. It lifts the holster on my leg. However, if I give just a slight “twist” to the grip (Pulling the muzzle of the gun away from my leg, and pushing on the backstrap of the gun with my palm), it clears fairly easily. It’s still noticeably slower, but if I were to ever not quite get the hood latched all the way, I doubt the gun would go anywhere.
So, in review; Serpa is a much faster draw. I will continue to use a Serpa on my belt. But, I do not worry about my sidearm while in the Safariland holster. I put it in, and I could literally forget about it. Sometimes with the Serpa, I would reach down “Just to check”. I would imagine, with some rounds down range, the Safariland will start to prove fast enough over time. I’ve played with it for about an hour. I’ve been using my Serpa Mon-Thurs for two years. I don’t think it will ever be as fast as a Serpa, but I bet I could get close.
I haven’t decided which is more comfortable. I’ll let you know (my personal opinion) Monday evening when I get home.