I am basically in the same situation. However, because I am a home user, I will go for a X10SAT. I dont need more than 32GB RAM in a foreseeable future. I will not virtualize more than 2-3 VMs I think. Those fit into 10GB RAM easily, then I have 22GB left. I could virtualize 10 VMs giving 2GB each, which would give me 12GB RAM leftover. Why would I virtualize 10 VMs? I dont have need of that.
PCIe lanes can be a problem on a X10SAT. But, if I added a quad GB NIC, I would insert it into the PCIe v2 slot. Sure it is only 1x speed, but that is the equivalent of 500MB/sec. So, I have three 1x slots, each giving 500MB/Sec. That is plenty for my small needs. I am going to add a HBA card too, an IBM M1015 (rebranded LSI2008) into a 1x slot - which will give me 500MB/sec instead of the full 1GB/sec speed. This is also ok for my small needs. I can wait an extra 1 minute when copying stuff. 500MB/sec or 1GB/sec - that is not important to me.
Then I can still use a 16x PCIe v3 slot. Or two 8x PCIe v3 slots. But the fastest graphics card out there that moves tons of pixels at insane speeds, do not saturate a 8x PCIe v3 slot today. It is no difference if you insert the fastest graphics card into 8x or 16x. Just look at some graphics benchmarks comparing 8x to 16x - no difference. Well, there might be 2-3 fps difference in some cases, but that is practically, "no difference". So, I can use a 8x slot for my graphics card. Then I have another 8x slot for something else. Like... Xeon Phi compute card? But first of all, Phi is very expensive, so I can not afford them, second, if a ultra fast graphics card is happy in a 8x slot, then the Phi will also do fine in a 8x slot. And if the Phi does not fine, it might slow down a bit in 8x slots, in worst case. Maybe it slows down... 10%? So what is 10%? Do I really care? Can I wait another minute or half an hour? Yes we can.
Sure, it would be nice with 256GB RAM and 40 PCIe v3 lanes, but that is overkill for me as a small home user. Most probably I will not use half the resources. And if I really need the resources, I buy a dedicated PC to do that stuff that I can not wait another half an hour for. Most probably I will be fine, waiting another half an hour. And the new Xeon Haswell E3v3 cpus are very fast actually. The threads are very strong, in par with hexa core cpus or so. But the only difference is that with hexacore, you get more of the threads. Can I wait another 1 minute? Yes we can.
I would like to build a silent audio station to create music. And a powerful gaming PC. So, should I build them? No. Instead I build a silent gaming PC using the X10SAT, and then I simply buy a 3.5" hard disk caddy, so I can easily swap hard disk. So, I have one hard disk configured as a audio station, ASIO drivers, installed music software, etc. Then I have another hard disk configured for gaming, installed all games, etc. And when I want to create music, I power down the PC and swap disks. Sure, it is a nuisance to power down the PC, but can I wait another 5 minutes before creating music? Yes we can. I do not create music while playing games, so my PC does only one task at a time, so I can swap disks. Sure, if I needed to game whilst creating music, I would need two PCs. But I dont. And I need to wait another 5 minutes to switch tasks. But that is ok for my small needs. I am not a company where a 5 minute wait would be disastrous. People building music workstations are building separate a PC with only the OS and nothing else, it is not even connected to the internet. They are only using it for music, and no extra software installed, because of lag which is really problematic, you dont want the antivirus software to run while you are recording to hard disk, using tons of software instruments - that would ruin the recording. Instead of buying another music PC, I can do that for the cost of another disk, which I swap.
Basically, I am not in a hurry, I can wait another minute. So I save a ton of money. And save space in my room. I will buy a DAS (16 disks in an external chassi) which I connect to my PC with the IBM M1015 card. So I can turn my PC into a file server whenever I need to, instead of buying an extra file server. That requires me to power down the PC and connect it to the DAS, but can I wait another minute before copying files? Yes we can. My DAS will never be connected, it will only be used as a backup. On my PC I will have a 4TB disk which I use for work, and then when I am done with the work I will backup to the DAS. The DAS is never connected, which means I am invulnerable to lightning strike. When lightning strikes, all your electronic hardware will be toast. I can always buy a new PC, but I can not recreate my data easily.