being based in NYC and FRA, and DL PM and LH SEN, i have flown SQ both first and business on this very route quite a few times...
by all means, fly first! i don't know about EWR-AMS, but JFK-FRA (every time i've flown it) has had megatop-747-400s with 12 seats in first...
by far the best transatlantic crossing method i've ever seen...