Hi Eduard,
I guess it depends on the definition of scientific value. Despite the Vela pulsar probably being one of most regularly looked at pulsar I was able to add some useful information about a couple of glitches.
If at the beginning I had looked at the extensive pro observations of Vela and decided not to bother I would have missed out on a lot of fun !!!
Sure - that effort didn't have the quality of the following pro investigations - but at least it brought attention to what we amateurs are capable of.
I believe during one of the recent down-under SARA zooms there was mention that the pros at Parkes are keen for an amateur radio astronomy group in South Australia to get involved with observing masers. There must be a reason for that.
But - yes - you are right - amateurs are generally not able to 'compete' against the pros - but it's fun trying and interesting as you say.
Cheers
Steve O