The 7800DX is going good so far. Sync speed is the same as the 7800N that it replaced and wireless range on 2.4G around the same.
The grey/silver paint job makes the 7800DX appear much more business like and expensive than the white 7800N that looked and felt rather cheap. It is still the same plastic box but does look much better.
The DX is made in Taiwan and not China like the 7800N, and appears to be better designed internally from what I can see in the vents. The Billion 7800N was shocking internally, with half stuck on as an afterthought heat-sinks (pic 1 pic 2), and glue/flux causing corrosion and wireless issues. The DX is using ceramic heat-sinks which seems to be becoming more popular (think of a small square tile stuck on top the chips). Overall the 7800DX seems to run cooler.
Billion need to update the web interface, it looks so dated. The silly thing is it wouldn't take more than a few hours of someone updating the style-sheet, and get rid of the women in the top left corner, pointless and tacky. While most people will only visit a few times for initial set-up, first impressions count, plus reviews will show this dated interface. The web interface is noticeably quicker to navigate around than it was on the 7800N which is an improvement.
Some things seem a little unfinished. For example you can set email details but what do you use them for? Seems the only time it will email is for a change of IP address, or if you log in remotely and use the "Push" option to get sent an email of the log and other settings. Would be good to have an option to schedule the emailing of these logs using the scheduling options, or to be emailed on Error or Warning logs.
Options for a Syslog seems to have disappeared! Edit, found at Configuration - System - Configure Log and change mode to Remote or Both.
UPnP opened ports now appear under Virtual Servers rather than having their own page and so show along with any other ports set up, which is a little confusing at first and could make it difficult to find and administer port mappings if someone has a busy network.
IP Filtering is restricted to just 32 entries.
Internet time settings has lost the option to set a resync frequency and I've seen nothing in the logs over the last few days to indicate it has resync'd the time. The time is currently 5 seconds off so hopefully will get updated soon and not continually drift.
Power management options, the Adaptive Voltage Scaling while set and reported as enabled in the interface, is showing as disabled via Telnet (pwrctl show). Not sure if this is a bug, or it has been deliberately disabled due to problems. I've enabled it just to see what happens.
The main plus point is it has been rock solid so far, although this does have the most recent firmware and it took a little while to get to this point. It has lots of specialised settings which I suspect most will leave at their defaults but good to have for the future.
It has tall rubber feet which allows for more air movement underneath it.
Note that it only has 4 Ethernet ports and not 5 like the 7800N.
The antennas are fixed because each one contains two antennas, one for 5GHz and one for 2.4GHz, but they can be moved to various positions to aid antenna diversity. I fell over a problem with 5GHz which meant it would not work with my phone, this seems to be because I set the channel on 5GHz to auto and it selected a channel not supported by phone. I suspect this is due to it choosing a channel that was outside the allowed channels for the country I'm in, I need to investigate where the fault lies. Billion has not got the 7800DZ Wi-Fi certified and considering the cost of these boxes that seems a bit cheap, however given they are just using what is essentially a Broadcom reference design it probably makes little different, but at least the Wi-Fi certification guarantees a minimum amount of interoperability testing has taken place.
Overall, I think the Billion 7800DX series is worth the money, it hasn't been dumb down and feature stripped to hit a price point, and support is very good.
Regards
Phil