To re-iterate some of the previous postings,If you can avoid the Teterhole by all means do so. It seems I spend half my life in and out of TEB and whenever possible we try to persuade our pax to use White Plains HPN. In fact I was there twice last week.
If trying to depart TEB between 1600 and 1730 be prepared for long delays and or ground stops. A number of times duty time has expired while waiting for engine start.
White Plains is far more customer friendly and is geared up for the NYC business clientelle. Some good FBOs as well.
As regards US customs, take heart from the fact that they are not prejudiced, they hate everyone equally !
As a Brit living and working here I have had many a fine run in with them. Thankfully at my home base airport the Company I work for arranged for a customs agent to be based on the field and so now life is much easier.
Remember if you must do battle with US Customs they are ex-colonials !
Good Luck.