Yes…without a doubt!!! The sound stage will be wider with improved clarity. BTW…just for correctness…there are no Sonos Five’s designated as Gen 2. The Gen2 designation refers to Sonos Play 5’s vs the Play 5 Gen 1.

There is a nice difference in a pair of Play 3s and a pair of Play 5 / Sonos Five. Most of what my poor quality ears hear is in the lower mid frequencies.

Worth the cost of the new Fives is going to have to be your call, don’t forget the ability to keep using the Play 3s in other locations, either paired or as singles.

A contrary view, especially if the cost of a 5 pair is a constraint, as it can be to many:

In the Sonos line up, on a standalone basis, sound quality and price goes up from the 1 to the 3 to the 5. Much of the improvement is on the lower midrange to bass delivery, with speaker enclosure size going up, as it especially does where the 5 is concerned. What this means that if a Sub is added to each paired unit, the value obtained for the price of the Sub is higher from a 1 pair as compared to from a 5 pair, because more of what the Sub does is missing from the 1 pair.

Adding a Sub therefore makes a big difference, but only in the case of the 1 and 3 units; the 5 is bass capable on its own. 

What this means is that by replacing the 3 pair with a 5 pair in your set up, you will likely not see the same Wow level of impact you saw by adding the Sub to the 3 pair.

This of course is subjective, and the value equations are even more subject to change from one person to the next.

Ideally: get the 5 pair on a test basis, replace the 3 pair by it, and see if the improvement you hear is worth the spend to you, to decide on whether to keep the 5 pair or return it.

I don’t have my pair of Play 5s any longer, took the first Sonos Trade-Up offer and got them bricked but there was a noticeable difference when I added the Sub to the pair. As said, it was less gain than the Play 1s or 3s saw.

I would argue that a lot depends on the space you’re using your speakers in.  If we are talking about a 10x10 room with 4 walls, then I don’t think you’ll see that much improvement in going from  3 to  5.  A 20x20 space, on the other hand, would see a big improvement in moving from 3 to 5.  

As for the benefit of adding a sub, perhaps it depends on what you’re used to.  I was used to Sonos sub with a pair of ones, beam, playbar, and arc.  I could tell the difference.  Never tested with 3s.  I fairly recently got a pair of 5s and could immediately tell that it lacked bass from what I was used to.  It definitely needed it, at least for the space I use it.