Not sure about EU countries lately, but years ago I traveled with loads of boards that we classified as "replacements" for the parts we needed. One of our techs actually filled two suitcases once and flew from the US to Frankfort and on to Moscow. I took them from there and to the customer, where I got the old boards to return to the company. Oddly, we didn't have any issues, though in thinking it through, he should have been caught without the returns and I should have had a problem with all the 'extra' stuff that I hadn't brought in......
On my trip to Ecuador two months ago, I brought in all kinds of electronics (I sold everything in the US and only brought two suitcases, a carry on and a 'personal item', all which had electronics in them in one form or another). I did get tagged to open everything and even though I had a computer, a cell phone, video camera, tons of cables, a projector and a full set of microphone equipment (mixer and three wireless mics which I use for teaching seminars, etc.), they only asked me about the mics, which are all mounted to a back board and custom fit into the hand carry suitcase. As I wasn't sure if/when I'd teach a seminar in Ecuador (and I had no clue how to explain that in my 50 or so words of Spanish!), I told them it was for my other 'primary' use - to sing karaoke (which I had intentions of doing). As I said that, a lady customs official came by and said "Karaoke? OK", and a lot of other words in Spanish that I didn't understand, but the guy that was picking through all my stuff just waived me on and let me re-pack everything (pushing me over onto the floor to let someone else get inspected.....) Once I got in country, I found out that karaoke here is about as mainstay as popcorn at a movie theater in the US!
I've taken pretty much the same setup (microphones, projector, computer, etc.) on several trips across the US (and once to Australia, via New Zealand) and always "plan" on getting stopped at security. A few times I didn't, but was always ready and certainly most of the time they want to open the bag, etc. I'd just explain that I was a professional speaker and it was my equipment for the seminar. Once, though, I was asked about the wiring going into the microphone receivers and when I told them it was something I designed myself as a "battery replacement" with some wires soldered onto wooden posts and run to a power source on the main power strip, I got taken into the back room........ - seems TSA doesn't like comments about 'build it yourself' type stuff...... :shock:
But, back to the Ecuador importing side, by the 'law', I was carrying too much to bring into the country and some of it should have been taxed and/or taken. I hadn't read the law before entering - never thought about there being a limit (after all, I wasn't doing anything "wrong" in my opinion and just never considered it). I am glad I didn't lose any of the stuff or have to pay a big fine to bring it in and certainly happy I didn't get tossed in jail!
You should really look at the current laws of the IMPORT side of where you are going as to what and how much you can bring into the country. It is very possible that there won't be a question about how much you take out, but bringing in is another story! And, the laws in each country vary, so check it out online (use search terms like "XCounty import law on electronics" - should be a good start).
One of the best things you can do though is to know that, should you unintentionally break the law, be honest and don't get in a fuss about it - letting them take it is much better than jail time!