I have seen the PNY solution and I think it would provide adequate security. My main issue with it is that I use my rMBP mostly in clamshell mode at the office and I would be very concerned about scratching the screen when closing the lid on it.
Switching to MacLocks, I pretty much think all their stuff is crap. I had the plastic skin case for some time but it added so much weight and caused the machine to get really hot. Also because it is poorly made, the corners did not quite mate with that of the MB. This resulted in 3 of 4 corners cracking. My other issue was for $80 they could not include a decent quality machine screw and driver. They include the cheapest, lowest quality, parts they can get. Furthermore, the plastic skin blocked the use of thunderbolt, usb, and even power when the apple power adapter was used. I had to file down the bottom skin in order to use my ports. I never tried it, but I am sure not much of a twist of the wrist with an installed lock would snap that pitiful plastic stem right off.
I also had a version of their plastic skin for the macbook air, but I returned it straight away since the lid portion did not stay on and the screws supplied did not fit (they were not the correct length due to the device's wedge shape). It took me 3 months to get reimbursed and they did not return but about half of the price even when I was promised a full refund due to its issues.
Finally, MacLocks then came out with the wedge. On their website they never show real pictures, only the 3d renders. I emailed asking for some pictures of it installed but did not receive a response. This latest one that goes on the bottom looks great in the 3D renders, but the pic posted to this thread looked like a poor quality pot metal cast rather than a machined piece that would actually have more strength.
I have no faith in MacLock's products. I think you could simply grab your machine from the lock while attached to the wedge and give it a good twist of the wrist like snapping a carrot in half. With the lock sticking out, there is an incredible amount of force on that thin walled cast opening.
I have been using the Kensington universal aluminum "wart" attached with 3M UHB foam. It does stick out on the corner but it is very secure and some serious damage would be done to the laptop if it was forcibly removed. For $10 I think it's the best option at the moment.
There was another product called Chicago Snake or something that did provide great security, but I did not like the idea of jamming metal inserts into my electrical ports.
In the end I really blame Apple for not providing (even proprietary) way to secure a $3,500.00 machine. They were able to change the magsafe port (just before patents run out i am sure and HyperMac could ship some products) but not provide a cable lock???? Shame on Apple for this. Apple is basically saying we don't give a **** if your machine gets ripped off.