The Macduffs have been kicking around that part of Perthshire since about 1160. In 1431, James I created one Finlay Duff the Feudal Baron of Fandowie. The family had the feudal Barony removed sometime after one of the family, John Macduff alias Barroun, was hanged in 1600 for his part in the infamous Gowrie conspiracy. John is my 9xGt Grandfather.
I have a copy of a tree headed "Macduffs of Strathbraan" which starts with Donald of Tomnagairn, who is noted as having been born in 1790. I think this is the same tree as others have - it was completed in the late 1980s, and appears to be fairly accurate. I also have a copy of my 3xgt grandfather's commonplace book, the original of which is with the University Archive in St Andrews. He was Alexander Macduff of Bonhard (1792-1842). In about 1816 he visited Fandowie and met an old man aged 90, called Donald Macduff of Tomnagrew, who gave Alexander the legendary history of the family. Alexander's son, Rev Dr John Ross Macduff, reproduced the account in his autobiography. This is obviously the same Donald as the Donald who was born in 1734. There are a number of Macduff families who hail from Strathbraan, the most important of which were the Macduffs of Fandowie and the Macduffs of Ballinloan. I think that the Tomnagrew family were connected to the Ballinloan branch, but I have no firm evidence of that yet!
This site is quite useful for more recent research:
http://freepages.genealogy.rootsweb.ancestry.com/~lendavies/allduffintro.htmLen Davies has done a bit of a one-name study and has compiled all of the Macduff records in the statutory records throughout the UK.
I hope that this is of some help/interest. I have more information on the Macduffs if it would be of interest.
Robert