Although I cannot give you a too technical feedback, here is my take. 

a) mine are running now more than 10 years  - no problem at all - sturdy built

b) you may know who the previous owner was and what his preference was (loud noise or else...)

c) physical check 

d) the set you may be purchasing may have limited warranty - seller liability

 

Overall and given that I have B&O gear spanning three decades, I have yet to encounter an issue based on lack of durability. You care and it gives back...So go for it if you are even able to test them. 

My dealer said they work best on a bookshelf etc where you can really work the passive radiators whatever that means

I think he means that if you put them close up to books or a surface they sound better.

I found that get sounded better when I connected them to the Avant than when I ran them on their own. You can adjust the db volume with the avant

I now have them plugged into an essence but am yet to work out how to adjust the db settings. But they sound good.

It was mentioned in a recent thread that the BL3 is also prone to deterioration.

I am on the forum via the app now, but I will search for it later. It was not substantiated, but might be worth looking into.

I have two pairs.

One pair was purchased new soon after I had the BL5's were introduced. No problem with them at all. The must be +13years old now

A second pair was purchased a few years ago (second life) and I think they are probably 6 years old. One speaker developed a fault and was repaired for a hundred-quid or so.

I think they are very reliable but best to keep them cool as there is not a lot of space in that cabinet and it is pack with drivers and electronics.

I bought a demo pair last year. 
When I asked my dealer about the BL3's lifespan he said nothing is on the horizon.

It's hard to update them due to the small cabinet space. No WISA or other stuff can fit inside.

In both design and quality I think a pair of Bl3 will last a long time.

 

//EA   

I have, quite literally, had hundreds of pairs - and I can say they are incredibly reliable. 

Lee

9 LEE wrote:

I have, quite literally, had hundreds of pairs - and I can say they are incredibly reliable.

Lee

Lee, are there any iterations to particularly avoid or seek out?

Perhaps in terms of serial number?

StKong wrote:

Lee, are there any iterations to particularly avoid or seek out?

Perhaps in terms of serial number?

No. None whatsoever. I'd be has happy buying a 10 year old pair as I would a 2 year old pair!

The one thing I would do, when/if you buy a pair, is use surge protectors. I've found that the only issue I've ever really had with these has been from 'dirty' power supplies.

Lee

9 LEE wrote:

No. None whatsoever. I'd be has happy buying a 10 year old pair as I would a 2 year old pair!

The one thing I would do, when/if you buy a pair, is use surge protectors. I've found that the only issue I've ever really had with these has been from 'dirty' power supplies.

Lee

Excellent! Thank you! Any comments vis à vis placement? Some in this forum are in favour of placing them on sturdy surfaces as opposed to wall mounting.