RME : peace of mind ... when i change it's for another RME 

RME Good.

I am feeling good about this decision!

I love my UFX. It's rock solid, sounds great and very versatile. I'm sure I'm still not using it to its full capacity. The only issue I've had with it is an XLR connection getting stuck. I am unable to remove it. It's still in there but it's a hassle and cost to send it away to get fixed and also a time out recording-wise. Of course I could temporarily go back to my Roland Quad Capture in the meantime but I like products that work consistently and where you received constant updated driver support...wish I could afford the 'plus' but maybe when I sell my car. lol

Do it. You won't regret it.

Same here, had a UFX for 4 years and I'll probably have mine for another 10 years.  The direct to USB recording is also killer. You can record every channel direct to a USB drive/stick simultaneous to recording to SONAR. If your computer crashes or locks up, you still have the direct recordings. For live shows I typically just record direct to USB and import them to Sonar later. 
 
gabo

Get it.  I have one and it's been fantastic.  Low latency, super stable drivers, frequent driver / firmware updates, etc.  totally happy.

Pragi
Are the firewire RME interfaces  able to run via a  thunderbird port?

They certainly run very well on a Mac Thunderbolt port using Apple's Thunderbolt->firewire adaptor and a firewire 400->800 conversion cable. Don't know whether that would work on a PC though. Not that it's a problem, the Fireface UFX works equally fine on USB2 or 3 as well. I only use its Firewire socket because my MacBook Pro only has two USB ports and I need them for other things. I spool audio to an external Thunderbolt drive so am left with just one spare Thunderbolt port to which I attach the UFX. To update the firmware actually requires it to be connected to a USB port on Mac or PC.
 
If I were buying a new one now, and having tried RME I'd be reluctant to go anywhere else without a very good reason, I'd go for the Thunderbolt/USB model. USB3.1 may be the latest thing, but with anything to do with computers if you hold off because something newer or the same thing for less money is just round the corner you'd never buy anything. Eventually you just have to get on with it or quit :-)

What is the diff between the UFX and the Fireface 802? They look very similar to me... Price-wise too.

Edit - Looks like 802 has arguably better audio specs but lacks direct USB recording and the display. UFX mix pres offer about another 10DB of gain.

Joining the RME praise-Choire: I have used my Fireface 400 almost everyday since 2007, it´s been out of production since at least 2013 & they released the latest drivers in December last year - so as long as the other hardware works, future compatibility is not something I´d worry much about.
The only problem I´ve had was that the PSU started making noises about 1-2 years ago, quickly & cheaply solved, I bought a new RME PSU for about 20-25$.
Other than that it has been rock steady through Windows Vista, Windows 7, Win 8/8.1 & so far Windows 10.