I've built the new board and tested some features. Have to visit local hackerspace to do more tests.
- DC works
- attenuator works
- attenuator values are really impractical (not very standard) and I'll probably have to buy them online
- test AC (need AC source)
- test DC offset (need 10k or similar pot)
- test overvoltage protection (need 9V source for arduino)
I've compiled the scope in windows 7 virtual machine as well and that went without any problems, so after I test the board I'll probably add windows executable to github.