Yes. I bought a Lowrance 3500 chart plotter, a 406 epirb and various smaller items eg, first aid kit, flares, emergency lighting sticks, MOB bouy, etc. They were prompt and efficient.
Usually bought stuff from them when they were doing one of their 'themed' specials - eg I bought a load of kit from them when they were doing a 'safety equipment month'- as generally found www.Boatbandit.com and www.defenderUS.com were generally better on price when not on special at Sailnet.
It just seems random. The chandler's ship it and sometimes customs charge and sometimes not. Not really any different from any other form of online shopping from the US.
Of course, you have to weigh up if the price differentials once shipping and possible taxes are added is worth your while.
Alternatively, if you have a US address that will accept delivery for you and you have friends or acquaintance who travel to the states regularly, you could have it brought back for you.
I read about myus.com in the Sunday Times. It seems they take items bought in the US, supply a US address to keep the website happy and then forward things on http://www.myus.com/