I strongly believe the issues with the 2820 are down to software, ie. Firmware and not a fundemental issue with the router.

Thinking back to firmware 3.3.3 and it was much more stable and reliable than what we have now.

That being said, I hope you are right that the 2830 is better for you. However given the price of these things, I can't justify spending that much again for a router that looks identical (on the outside at least).

Looking at the online demo there doesn't appear to be much different to the 2820. Users and multiple LANs and thats about it from what I can see.
Supposed to be 5GHz wireless but I can't find any option for it.

http://www.draytek.com/.upload/Demo/Vigor2830_v3.3.6/

Broadbandbuyer are stating the 2830vn is not due until 14th April - is this true?

Yes, was told the same story

I've pre purchased one , it's probably down to V ( additional accessories for VoIP like voucher and the pstn adaptors )

Only 50mb throughput from the firewall. As broadband speeds get faster this unit hasn't got much shelf life left in it. I would have thought it would have had at least 100mb.

As ADSL2+ is limited to 24Mb/s, that's adequate for most scenarios. If you need higher across two WAN ports, you can use a vigor2920 (with one Vigor120 is needed)