I do think if you want a shorter arrow and only plan on putting 200 upfront, you may be over-spined. But, if shooting a longer arrow with 250 up front and pulling at least 50#, 55/75 should work for many efficient bows with FF string. I was surprised how much I had to cut down the 55/75s to get them to work. There is no way 35/55 would work for me with 250 up front. I agree on test kit or seeing if someone can loan or give you a 400 spine arrow to play around with before buying a dozen.
Tom, I chose GTs because they were lighter for spine, that way I could put 250 up front and still have about a 10gpi arrow (515 grains v. 570 in 150s or 600 in 250s). But this year I'm trying Trad Only's, which are a little heavier.