I currently own a Rocket R9 One. Before taking the plunge on it I had some of the same concerns as you, in fact I even requested pics from my vendor with the top and side panels off. They were kind enough to send some over. The layout isn't as neat as my previous Pro700, but it also wasn't near as bad as others.
Some of the points that made me go with the R9 were the saturated group, on/off schedule, programmable and manual profiling that can be saved, big steam power and mixed water wand. The only major thing I wanted in a machine that it didn't have was gravimetrics. After over a year of use it is still something I desire. I had pondered about the DE1 for some time but couldn't get past the low steam power and vibe pumps. I also had a worry of software bugs and even the over all appearance of the machine. When I pulled the trigger on my Rocket the 1st version of the DE1 was being released, now I see there's been a few versions since. I have no doubt it performs well, but it just wasn't my cup of tea and frankly I don't think my espresso skills are good enough to be utilizing all of its temp, pressure and flow features. I'm willing to bet that most home baristas don't either. Even with my Rocket I've come tired of playing with so many different variables and profiles that I have a couple go to's and I tend to stick with those. Funny how that worked out.....at least I still have the option to play around if I so desire!
Over all I'm very happy with the machine, but that wasn't the case from the beginning. One major problem I was having was the repeatability of my shots when using saved profiles. The outputs would be all over the place. If my desired output was 40g my results could range anywhere from 20-50 grams, almost always they were far lower. This was more so the case with long slow pre-infusions. I had reached out to both my vendor and Rocket. To my surprise Rockets customer support was absolutely horrible. I tried for weeks to resolve this with them, even going as far as documenting all my shots and sending videos. Their reply was that the flow meter they use is of commercial grade and used by countless other manufacturers.
I ended up spending countless hours trying to troubleshoot this issue myself and finally figuring out that I needed to do a high pressure flush with a minimum of about 30-40ml of water before any shot while using saved profiles....
This leads to This machines biggest downfall IMO. As noted above, a high pressure flush is needed before using saved profiles to be accurate within 1-2g of desired output. What's annoying about this is that if your saved profile has a long low pressure beginning, you have to cycle through to the manual profile which uses the group head actuator, or another profile that has a saved high pressure to flush for 4-5 seconds. Then cycle back to the desired profile for the shot. Very annoying. The only thing I can think of that is causing this, is that the water path from the flow meter to the group head drains somehow. When a shot is initiated it has to make up this void of water in that path. When the flow meter sees the predetermined amount of ml's saved in the profile and stops the pump, the amount of water gone through the puck is substantially less. I came to this conclusion by noticing how many ml's it takes to fill my basket. Without flushing before a shot it will take around 56ml of water for the basket to fill and the shot to begin dripping. During a normal pull with a flush before, that number is 32ml every time. Now if the saved profile stops the shot at say 76ml and it takes 56ml to just fill the basket, the last 20ml of the profile results to near nothing in the cup. I hope this makes sense. When profiles are more traditional and a higher pressure is reached in a reasonable amount of time at the beginning of a shot, you can quickly flush the group without having to change profiles and there's never an issue. Luckily for me I don't use slayer style shots very often so I can use this method which is quick and easy. I flush while my grinder is emptying, dry my portafilter, prep and pull my shot.
Some other cons to this machine are the limited height between the group head and drip tray, only certain coffee cups fit with a scale underneath. Espresso cups are no issue. Im certain this is most likely a standard distance and I was just spoiled with my Pro700 before. The drip tray doesn't drain well and lastly the shot screen doesn't stay active long enough after the shot is finished. When I'm steaming milk and a shot finishes, if I don't look over immediately it returns to the regular screen. I always like to see my time, pressure and ml's after each shot and compare it to my output weight. Small items yes, but I still feel I should mention them. Some may complain about the touch screen, but for myself I've become used to it. It is by no means as responsive as the latest smart phones, but there is no lag or delay with any functions. I use my thumb to press the icons and have no issues. For those who use their index finger, at times the screen won't respond. It's more of a footprint issue rather then a product problem, the glass screen seems to need a certain area pressed for it to react.
All in all, after over a year of use I'm quite happy with the machine. If it had gravimetrics the biggest issue of the machine would be solved! I'd trade a flow meter for a scale in a heart beat!
At this point I don't see a perfect home machine out there on the market. When I compare what's out there to the R9 One, I'm happy with my purchase. If you have any questions I'd be happy to answer them the best I can.