I agree - 2000 is definitely the end of "early years" Home and Away:
Two long-serving characters departed the show: Ailsa, an original character, and Sam, who had been around for 9 of the 12 years.
A number of "classic" characters also departed in late 1999 and 2000 such as Mariyln, Rebecca, Travis and Chloe.
The loss of two long-standing sets: the original Diner and the Stewart house.
The arrival of the Sutherlands. While 2000 was sort of their "ease them in" period, 2001-2004 was basically "the Sutherland show", so at times, it felt like an entirely different show, especially when coupled with the other points I made.
A number of other characters departed in 2000/early 2001 (the Nashes, Peta, Edward, Judith, Ken, Harry, Mitch) but I don't count their exits as "the end of the era" like I do with those mentioned above as they aren't iconic to most fans, nor were they long-serving.
It will be interesting to see when/if the 7two repeats ever lose the "Early Years" tag, but for me, it would come in the final episode of 2000.