rendering is not made faster by MORE RAM. It is made faster by a better GPU. RAM with a higher bus speed is also beneficial. Also, WHERE THE HELL did you get 2 32GB DDR3 sets for $200.00 each?!?!?!?!
Of course it is. As long as you have a 64-Bit Processor and enough ports, you can put that much RAM in it. For example: An Intel Core Duo can only handle up to ~3.6 GBs of RAM. An Intel Core i7-3960X can take up to 64GBs.
Well, with better ram you can simply hold more textures and more things on your screen. Even things that haven't actually been rendered yet are things loaded onto your ram just waiting to show up on your screen. The only problem is that you can actually slowdown your game by allocating too much ram to Minecraft because it needs to keep all that data in sync and keep updating it. I would imagine allocating 60GB of ram to your Minecraft is a bit overkill and that you may experience a significant slowdown.
Holding more textures is mainly done by GPU I-RAM. Minecraft also uploads world render matrices to the GPU I-RAM. The regular RAM is usually used up for double-buffering the uploaded data, world data, and other things that the CPU processes. Now, allocating too much RAM shouldn't slow down Minecraft as long as you have enough PHYSICAL RAM to hold it all. The problem arises when you start to use the PAGING FILE, which is basically your hard drive acting as a temporary storage area for RAM. If you have 64GB of RAM and you allocate 60 of it to Minecraft, it is overkill, but as long as you are not doing too many other things, it should not slow down the system. Now allocating 20GB to Java's Permanent Generation IS NOT ADVISABLE. Nobody in their right mind would make a Java program w/ more than 20 GB of OBJECT TYPE DEFINITIONS. That entails a program that is at least 35 GB large, akin to a FEW games, but they are not in Java. Java will probably shit itself if it needs to handle 20GB of shiz. TL;DR: GK, you are wrong on everything other than overkill. 20GB for perm gen is really, really bad.