Let me give you the benefit of my experience. I paid a bunch of points (4) when I bought my first house for similar reasons than you mentioned including:
- Lower interest rate would result in savings over life of 30yr loan
- I had a big capital gain from cashing out stocks for the house down payment and the points (as interest) would offset the tax liability.
Why I wish I hadn't:
(1) Interest rates plummeted (not as likely to happen today) and I wound up refinancing the loan within the fist 10 years negating the savings that I would have had over the life of the loan. Also, it made me feel stupid for paying close to $5K to knock 1% or so off the loan rate only to have an even lower rate offered to me with no points within a decade.
(2) I didn't take into account that I'm the type of person who would try to pay the loan off early, and I did. Way Early. So even if I hadn't refinanced, the extra points were really a waste of money.
(3) In the US, at least, you can't always deduct ALL of the money you paid in points in the first year. You may have to spread that deduction over several years.
(4) You are right about the alternative being better (investing the points), since the benefit of paying them is at most 1-2% on your loan, you don't even need a 6-7% return to make it a better deal to invest them. HOWEVER, I get skeptical when people compare paying interest to returns on invested money like that. If you don't pay the points will you actually invest that money for the 30 years (or whatever the term of the loan is)? It's easy to say that when you are talking theoreticals, but $5k in your pocket is also pretty tempting when the deal is done.
Good luck with the new house!