I have trained with the same sensei for a number of years. He is a great guy (like an uncle to me) and very skilled in what he does. I feel that I have learned a great deal from him and I could still learn a great deal from him.
BUT . . . . . . . . :
*After multiple seminars and visiting other dojo I seriously wonder if our dojo's brand/style/flavor of aikido is congruent to the national org. and hombu. Kihon is WAY different, names of arts differ, attack dynamics are different. Yudansha exams are done by the national org and I worry that I (and others) won't be doing things the way the Shihan or testing committee wants come test time.
If you are talking Aikikai, there is not one particular way of doing technique that is congruent with Hombu while other ways are not. There are very different ways of training within the Aikikai. Students of different Japanese Shihan differ quite a lot.
Are there many countries where a national testing committé gives dan rank? I only know of Sweden and France, but my info could very well be outdated here. If indeed you are in Sweden, if you choose to take rank for a shihan IMO your style of aikido should be somewhat similar to the shihans in question. Some teachers are more open to stylistic variation than others, but if your teachers's line of aikido don't have a regularly visiting shihan probably the national grading committée is a better choice. They are used to judge aikido from quite different styles within the Aikikai; that is their task, and different "styles" within the Aikikai is represented in the committee.
That a certain way of doing aikido is less common in the country in question and the names of techniques differ, doesn't mean it is bad or not accepted. For instance, there is one aikido teacher in Sweden whose main inspiration is late Akira Tohei sensei - probably misspelled, I am referring to the Tohei sensei who lived in the US, not the Tohei sensei of ki-aikido. In this teacher had stayed in the US his style wouldn't be so uncommon, but here he is the only one. I am convinced this will be no problem for his students regarding gaining dan ranks.
I am in no way involved with the aikido politics - in fact I don't train any more, but I still consider myself fairly informed in these matters. If you are from Sweden and would like some more informal info, feel free to send me an email through Aikiweb. Still, I think it would be good if you could talk to your teachers regarding your concern about gradings, and his style and terminology being different from others. If he is worthy of your trust, he should have some good explanation for the differences - like explaining his aikido lineage (who was his teachers, and who were their teachers).