Current Precision 5510 owner
I've been running a 5510 model with Xeon, 32 GB and SSD for the past 2+ years and it is a beast.
My work entails building virtual PoCs comprised of multiple servers, routing, firewalls, IPS etc. and so far, this thing was able to handle everything I throw at it.
Battery life could've been better, but it is hard to expect the system used in this fashion to last long when unplugged.
Running Win10 Pro, VMware Workstation with nested ESXi(s).
I suspect that the 7 series is the improved version and will likely be the one I'll upgrade to, if my current one gives up the ghost.
The only issues of note are absence of the fingerprint reader and the smardcard slot.
The 15" screen is a 4k, but I had to dial it down to 1080p, since some of the apps were not scaling properly and I did not have a microscope handy.