PowerConnect switches are OEM'd by Delta Networks, from Taiwan.
I'm using 6248's and 6224's with two Customers (one using powered and one usign non-powered versions). They're much cheaper than a feature-similiar Cisco switch, and they've worked well. The first Customer got theirs in late 2007, and the second in fall of 2008.
We're only using layer-3 functionality on the 62xx's at one Customer site, but it has been working well. They do not have very fancy layer-3 entities, but then you should probably be usign a router if you need really fancy. I am using layer-2 VLANs at both sites, and they work fine.
We have the RPS-600 on both installations and I've verified that the RPS works as advertised. (In fact, the cabling company pulled the UPS feeding the AC on the switches, but not the RPS, and no one at the Customer site noticed they'd been running on RPS for several days.)
I recently upgraded the firmware on the older installation and one of the switches continually reported a problem with its flash filesystem. I called Dell support and they sent out a replacement switch with very few questiosn asked.
We opted, since the switches were so inexpensive (as compared to the warranty support), to purchase a "cold standby" switch at each site in lieu of fancy on-site warranty. The entire switch stack, in the case of the 2007 Customer, w/ three 6248's and an RPS-600, cost less than a single one of the 48-port Cisco switch a vendor quoted (a 3560, I think... I don't recall now. It was expensive.).
The configuration command-line interface is Cisco-esque and close enough that I almost forget that I'm using a non-Cisco switch. (The "configure" command not taking the "terminal" argument irritates me-- I'm all the time typing "conf term".) The web interface is reasonable, though I prefer the CLI.
We are using MRTG at both sites to collect statistics from these switches. They work as expected w/ respect to SNMP.