Unfortunately there is no "perfect" cage. As an owner of 36 Vision cages used to house rattlesnakes let me tell you how much fun I've had over the years with them.
The locks are ugly and cumbersome but something that you should probably learn to live with. I have a sealed room with sealed tileboard walls, sealed door and concrete floor for the snakes. That security made me gave up on the locks after the first year or so because they would obstruct my view, leave marks on the glass, get feces on them, jam and have to be broken to be removed (read that buy new doors) and the most fun of all is that if you intend on breeding any small species you will have to plug the gap between doors and that can't be done with the locks. I have never had a rattlesnake push the door open. Burrowing species or constrictors with more "push" might be able to open the doors.
The "lip" is also a constant source of entertainment. If you keep one snake in one cage with no cage furniture and you don't see the snake, you know it's on the lip. When you keep pairs or more in a single cage and have rocks, wood, or other fun stuff in the cages you don't know where the snake is when you can't see it. I had to make a special mirror so I could scan the cage lips, what a treat when looking for a venomous snake. I also made some special hooks for removing snakes from the lip, yet another treat. If scanning for your snakes with a little mirror and trying to extricate them with a 90 degree hook sounds fun (it can be during the winter when you haven't been hunting for awhile) go for it. Snakes also seem to think the "lip" is their toilet. If you have a litter the neonates seem to thing the "lip" is a nursery. If you ever want to clean your cages the "lip" keeps you from being able to clean the cage by washing/flushing with water. Most of my cages have been expandable spray foam around the lips to fill the gap. This cuts out the nonsense of the disappearing snakes but doesn't help with the cleaning.
The heat/light issue is an easy fix with some models that have the elongated recess for fluorescent lights. If you stack the cages the light from the cage below heats the cage above. Heat tape behind or between the rows works but heat tape itself is inherently dangerous. If the tape is placed between 2 rows it heats both sides and cuts down on the amount of heat tape required. There have been MANY fires and meltdowns due to heat tape. Your best bet is a room with controlled ambient temps.
On the issue of stacking cages (which they are supposedly designed for) I have mine in stacks 4 cages high, you might as well buy a hi-lift jack to get the doors out of the bottom rows. Over a couple years time my bottom row cages have become "pregnant" bowing out at the sides and crushing down on the door frame making the doors stick and impossible to remove without prying the frames open. Another thing you'll notice when dealing with multiple cages is the inconsistency in size. There is up to 3/8" of difference in height on mine within the same models. After careful consideration and measuring of all units I have them in rows according to rough exterior size so I don't have a wacky shack appearance. Shims can eliminate some of this problem when there is only a minor difference in size.
Now for my absolute favorite problem with the Vision cages. The tracks for the doors and the gaps between the doors. Let me say first that I have NEVER lost a venomous snake. Outside of the snake room that is. I have however had a good many neonate rattlesnakes and some copperheads release themselves from their cages. The track for the doors is a catch all for bedding, feces and anything else you don't want stuck in it. I really see no way around this with sliding doors. Most of my cages are now single door units because I have filled the gap for the interior door to keep debris out of it, this also effectively locks that door. The exterior door track is also blocked as a locked. This keeps ugly locks out of the line of sight and keeps debris out of the track. I just pull the blocks out when I need to open the doors or clean. I also have clear plastic spacers for the gaps between the doors. I found these were necessary after 2 litters of sistrurus, a littler of copperheads and a couple of baby lepidus found their ways between the doors while I was out of town. There is no greater thrill than walking into your snake room after a 9 day hunting trip and a 900 mile drive home to find it crawling with baby venomous reptiles. PLUG YOUR GAPS!
OK, there are all my observations on the design flaws of Vision cages. As for the good points they look nice when clean. There is no better alternative that I have found for sale. It's expensive and time consuming to build your own.
. The heat panel is screwed into the inside roof of the cage on one corner (the screws come out through the top of the outside roof but can be easily cut to allow for stacking). The panels are then attached to a Spyder Robotics thermostat to create the proper thermal gradient. We then have a fluorescent fixture w/18" full spectrum bulb providing light through the back vent. For lepidus, we keep them in the 222's (28x24x24) and simply heat the cages with a drop in heat lamp and a 60 or 75 watt Verilux lamp) which provides a gradient ranging from the low 70's on the cool side to the low to mid 80's warm side with a basking area (under the heat panel) that reaches the low 90's for 4-6 hours daily). Night temps drop to ambient room temps at around 70-72 deg F. I like the higher model for lepidus as it allows me to get a nice stack of flat rocks to provide thermal regulatory opportunities for this rock loving rattler. Hope this helps.
