My DS is a different race to me.
You need to think it through quite carefully before deciding.
A few things to think about:
1 - children who are transracially adopted with two white parents do tend to get stared at quite a lot - they don;t get much privacy out as a family unless they are only with one of you. I'm a single parent and so everyone just assumed that I have an asian partner.
2 - racial mix of school in my experience makes a BIG difference. DS's school is very very mixed, all sorts of ethnicities and mixes of ethnicities. It has helped DS not feel too different.
3 - be prepared to deal with racism large and small - from gormless adults calling your child "chinkie" (in our case) to children calling him "japanese boy" but everyone else by their names.
4 - be prepared for the fact that you don;t adopt a child of a different race, you become a multiracial family. This might sound a bit obvious but it was a bit of a revelation to me. Having children of a different race to you is not like bolting on an optional extra - your perceptions and family change from the inside out.
5 - it adds a dimension to an already complicated mix - in additional to the ususal adoption issues (whatever they may be in your case) you have the added issues of a child who doesn't like their skin colour or their eye shape and you have to incorporate ways of valuing difference if possible way before that becomes an issue.
Not sure if that helps.
And for the avoidance of doubt, DS is the best thing I've ever done but ethnicity/race/colour etc does matter. It's just not insurmountable.