Hi, I hope Meg's Mom doesn't mind, I am excerpting below some good advice she previously gave me about the catnap. My DS is 7.5 mos and still takes his catnap. Even when great sleeping on the other naps, he has been fighting the catnap literally for months but almost always eventually takes the nap -- has only missed it twice in recent memory. I've actually found since DS has become much more mobile in the past week or so, he is getting tired more easily and better about taking the catnap. So, I plan to keep offering it to him until, as Meg's Mom suggested --
Anyway, I think you should follow your instincts and stick w/ your current routine until:
1) he refuses his catnap for several days in a row
2) refuses other naps "
3) catnap gets so late that bedtime is moved back again...you are on the verge of getting too late.
4) nightwaking come back or increase.
PS: when he does drop the catnap, he won't go 4hr till bedtime...you will increase A times between the 2 naps so it is more like 2.5/3.0/3.0.