Your traveling class of service doesn't matter. In any country, there is no such rule that premium class pax are screened for customs less frequently than the general public. If you have a lot of luggage, it's usually the main target for the customs officers. If you plan on bringing electronics, make sure you present some indication that the items are "used" and are for your own private use. Also, you have to be aware of local customs law where most countries have special examptions to their citizens who are returning to the country after official long absence (ex. immigrated to another country but returning, or returning from long term foriegn assignment).