You are completely right. The X61s is a better design (I happen to own one too!), I completely forgot about it as, due to its much slower CPU, I must have put it away somewhere in the attic many years ago :)
Slow by modern standards, being pre-Nehalem, yes. But not 32-bit, the X61s tops out at a 1.8Ghz c2d L7700, which is 64-bit:
https://ark.intel.com/content/www/us/en/ark/products/32243/i...
Intel® Turbo Boost Technology: No
Intel® Hyper-Threading Technology: No
Intel® Virtualization Technology (VT-x): Yes
Intel® 64: Yes
Instruction Set: 64-bit
Enhanced Intel SpeedStep® Technology: Yes
Intel® Demand Based Switching: No