As a person who was diagnosed by a specialist psychologist as an adult, I would recommend it to others, with a couple of cautions.
First the cautions. It might cost very little if you live in the UK, but it might cost a lot if you live in the US. I live in Australia and it cost me the equivalent of US$500 for the whole diagnostic assessment process. I have heard of people paying US$1-2K for a diagnostic assessment in America. Only you can tell how much it will cost and whether that price is worth it. But I can say that I am very glad I paid my US$500.
Second - and this surprised me. I wanted the diagnosis and am glad that I got it. But I had a negative reaction for a while: all the internalised stigma came to the fore: "You are broken. You are second rate. etc" This was depressing. Society has a strong negative message about autism, and you may be on the receiving end of that from yourself if you get a diagnosis. What got me past this reaction was doing something very positive with my diagnosis. I took up tutoring gifted high school students with Asperger's who are into games programming. The school is very pleased, and they know all about my diagnosis. I am there as the adult Aspie computer programmer who can relate to the student Aspies on their terms. And I can teach programming skills that none of the school's teachers have. After a few months I realised that this was very therapeutic: my diagnosis was a qualification for doing something positive ... and I might add that I was partly inspired to do this by listening to some of Temple Grandin's talks. With more time I would consider setting up a computer club for high school students on the spectrum - and I would love to have other adult Aspies involved (well, I am in Australia, so most Slashdotters are too far away.)
A really good talk on Asperger's and adult diagnosis is here (45 minutes): https://www.youtube.com/watch?...
She discusses what getting diagnosed means for her as an adult. The talk gets more personal as it goes on - she starts with more general information and then gets into how it affects her life day to day. I have similar experiences to her with phone calls, burn out, fluorescent lights, sounds, and general social overload. I am trying to take better care of myself and get less burnt out - her video helped me identify that a little better.
As for positives about getting a diagnosis ... First of all, it gives you certainty instead of doubt. You can move on with learning how to cope better with your weaknesses and strengths, rather than going round in circles: "Am I or aren't I?" If you don't have the label "Asperger's" then by default you get the label "normal" - and that might not be an appropriate fit for you. Many Aspies - diagnosed and undiagnosed - spend years of adult life trying to "fake normal" and suffering fatigue or burn out (including break downs) or even meltdowns.
Second, it opens up participation in the online community where you can learn from other people on the spectrum. I have found that very helpful - one example being the video I linked to and another being Temple Grandin's own talks. There's also the web site Wrong Planet, and even the Aspies who post regularly on Quora, answering all sorts of questions about autism. There are many helpful blogs around too where you can learn from other Aspies who have thought about and discussed their experience on the spectrum.
Third, you may want some counseling or therapy, either now of in the future, to deal with issues like stress, anxiety, depression, or even marriage counseling. Having a diagnosis and seeing an adult autism specialist will enable that therapist to adapt their approach and therapy to your real condition. The autism spectrum has a major impact on how people process and handle emotions and thought, so counseling and therapy need to be handled a bit differently with Aspies - especially things like marriage counseling which involves both emotions and social interaction - things that Aspies do differently to the non-autistic world. Even medication can be affected by being on the spectrum. I saw my diagnostician for two years and learned about managing stress and anxiety and some serious sensory sensitivity - still applying those lessons now.
Even if you are coping well now, you might find that your ability to "fake normal" wears off as you get older. All the effort trying to appear "normal" can cause burn out and as you get older you may revert to more overtly Aspie behaviour. The coping skills may become weaker. And a diagnosis will help both you and other people to recognise and handle this better.
Good luck with whatever you choose to do. In any case, get books and read. Look around the web and read. Learn