Sorry for the hiatus; I've been quite busy.
We've been contacted by and received a proposal from Nimble in January. It looked good on paper, but replacing only the SAN doesn't fix our node resources problem (not really a problem now, but will be sooner than later). Also, regardless of the company, if we only upgrade the SAN, then we'll be corned in another "nodes+SAN" architecture. I'd really like the management simplicity of an hyper-converged architecture.
If we go with Nutanix, we'll convert the Hyper-V VM to Acropolis (their hypervisor).
Yes, the 3PAR is a disk array. Our needs are to have a robust architecture with enough resources to support the production environment for several years and reliable replication to a DR site. We already have a DR setup, but Veeam replication leaves a lot to desire. It's been unreliable in our environment. Not something new. We've used Veeam since version 7 (which was crap for Hyper-V). Version 8 worked better, but version 9 and 9.5 fail to take snapshots from 3 of the VMs. We call the support, it gets fixed and a few months of Windows updates later, it breaks again. Overall, Veeam simply hasn't been dependable for us. Veeam also doesn't work on Nutanix's Acropolis.
The RAM issue can be fixed easily if I manually balance the VMs on the host to balance the load, but an Hyper-V failover cluster doesn't efficiently distribute the VMs on the hosts when one host goes down. So if we keep using Hyper-V, we'll need to upgrade the nodes to ensure that we have a lot of spare resources on each host. According to the Nutanix talking heads, their cluster does a much better and simpler job of distributing the load. They demoed it numerous times too, but of course, the salesmen always show the shining parts.
I've not received the prices yet, but if the offers have similar cost, Nutanix's architecture looks quite good. I'd really like to find out what you found to perform poorly two years ago. I understand that you cannot disclose it due to the agreement you've had with them. Depending on what doesn't work well on their solution, it might or might not affect us for our use. So maybe it's a non-issue in our case.
Comparing Nutanix to a Windows Hyper-V cluster and Storage Space Direct volume, Nutanix has the advantage of data locality on the nodes. S2D doesn't apparently try to move the most used data on the node that uses it, so that's why it's a lot more demanding on the networking side (which means $$ for the switches). The nodes also all have to be the same, so no mix-generation nodes within the cluster, which isn't the case with Nutanix. However, with S2D, it's more of a DIY architecture, so there's more hardware choices than what Nutanix offers for their nodes. It also possible to use more generic component, bringing the cost down. The downside of this is multi-vendor support, so they can all throw the ball to each other when issues arises.
I've not considered Dell or HPE's HC380 yet and I don't think I will either. Dell's support could be better around here and HPE's hyper-converged solution isn't what HPE's guys want to sell us, which means they won't give us a good discount for it.
Regarding the budget, it's in the low six-figures (~150KU$).