If they have what you want in stock then they are ok. They advertise all ex-dem/graded stuff mainly but you should be ok new boxed items. Make sure they are authorised dealers for whatever you buy. I have only ever bought a small sub for my pc and it was fine.
Just bought a Pioneer mp3 player for the car from Hiwayhifi.
The first unit had scuff marks across the display so I phoned on Saturday to arrange an exchange.
They were very good and arranged for shipment of a new unit and collection of the first which happened yesterday (Tuesday).
Unbelievably the second unit had exactly the same marks on.
Just got off the phone and they have arranged for a full refund with no argument.
I spoke with the sales manager form the shop floor who was very apologetic but blamed the drive towards cheaper units and poor packaging and basically said if he sent another unit it would almost certainly be exactly the same as the first two.
To contrast I bought a Pioneer head unit two years ago which came with a peel off strip on the display and was totally encased in a custom fit polystyrene case. No marks at all.
The two I received from Hiway had no peel off strip and were almost loose in the box supported by pressed out cardboard cutouts, one of which was supporting the head unit display.
Both units were brand new and untouched as far as I could see, confirmed by the manager I spoke with.
Looks to me like the displays get scuffed as they rub in the box during shipment.
Anyway, full marks for Hiway customer service.....not so sure about Pioneer though.....