Yes, collectors tend to be a good lot, so you will have few (if any) problems, especially if they are a member a philatelic society.
I was wondering more about forms, fees, taxes, duties, inspections and customs regulations that would gum up a trade. I don't know if any are applicable for stamps but I've heard some horror stories from others that have sold items internationally.
That's where the real problem exists. For stamps coming into the US, there is really no problem as few items exceed the import limitation threshold. The only restricted stamps are DPRK and Cuba, but I've never known the state/treasury departments to enforce this unless they were revenues found in a passport.
For stamps being sold to other countries, this IS a problem because many countries have VAT or other customs duties, and the threshold to trigger these is very very low, so it doesn't take a large sale get wind up with a hefty additional bill for the buyer. In addition, since many of the postal systems are now privatized (e.g., Canada, some European countries), some of them assess a basic charge just to calculate and bill the tax!! One friend was charged only 84c customs tax, but then charged $5 fee for calculating/assessing/collecting the tax!! I know that Royal Mail (Britain) charges an unbelievable £8 for this (in ADDITION to the actual tax!!).http://www.royalmail.com/portal/rm/...diaId=400362
The loudest and most common complaint I've heard involves Italy. Basically, stamps sent to the large cities are almost certain to be either rejected (very strict import restrictions involving certain stamps) or heavily taxed. Mailings to smaller cities seem to pass through unfettered.
Please keep in mind that my comments are in regard to stamp sales, not stamp trades. However, some countries do not distinguish between the two. In other words, bartering is taxable.