Enso,
I think late additions and FWH works great. I mostly brew IPAs, using FWH, late additions (15-20 and 5 or less) and dry/keg hops. I think of APA as an IPA, with less hops, grain and color. I'm sure someone with "more experience" will correct me :-). Take what I have to say with a grain of salt.
I punched your numbers into Beersmith (assuming 13% AA and 90 minute for the FWH) and you have 30.7 IBU. APA is 30-45 so you are barely in style (if you care). If you moved the 10 minute to 15 you have 33.5 IBU. Moving it to 20 minutes you have 35.7 IBU, which is still pretty low in my opinion.
If you really want to compare hops (assuming citrusy American hops here) I think more is better. I would go for high APA or IPA level of hops. You could easily double the hops to 6 oz (IMHO). I typically use 12-20 oz in 10 gallons of IPA/IIPA (including dry/keg hops).