I personally haven’t heard the 252, so couldn’t comment. It’s said that the 252 is certainly superior but there are many that don’t like it’s presentation so you would need to hear for yourself.
Recapping is advised every 10-15 years for the classic series.
Remember that if you wanted a 252 you’d need a Supercap to power it. Your Hicap won’t be able to do it.
I think a lot depends on your speakers and how large your room is. I recommended a 282/250 to Popeye a while ago, because he has large speakers that benefit from the control of a 250. But with easier speakers and / or a small room, the Supernait 3 may be all you need. I simplified my system recently and now have small speakers and a Supernait and I don’t feel it lacking. I suspect your B&Ws thrive on power. Changing speakers is another option and may be cheaper than upping the amplification.
I have about 30 square meters and my B&W 803 S are 15 years old. Actually I am very satisfied with my Setup, but a change of Speakers could also be an Option in some years. Which Speakers do you have?
The 252 needs a Burndy connection from a Supercap. I’d suggest you look at the main Naim website and learn what works with what, so you can make informed choices.
You will see I started this chat and I had the same set up as you (supernate 3/Hicap DR), I was also new to Naim so not clear on the upgrade path and benefits.
I can give you the benefit of my short progress with Naim and the advice from this forum.
This week I traded in my Supernate 3, it was a month old, against a new 250DR. I got a very good offer from the retailer. I then found the funds to purchase a new 282 and a second Hicap DR. For my room and set up I personally needed something more than the supernate 3 and hicap DR was offering.
The transformation is really significant, as you would expect. I listened to all variations of the SN3 upgrade path and all add improvements, the 282 the best improvement. From my own recent experience and if budget allows, I would enjoy the SN3/Hicap combo and plan for 282/250 and use your Hicap to power the 282, as this is probably where you will want to get to eventually. You can then add another Hicap DR or a Supercap DR to the 282. I decided against the Supercap due to significant increase in cost and Supercap is really there for a 252 combo, although most on this forum do say the Supercap is better which would be expected for the cost increase of a Supercap.
At the moment I am absolutely satisfied but as you know there is always a step more on the ladder to go. The way you went sounds also very realistic regarding the money you had to invest for a significant update. A 252 and a Supercap are far too much for my assets.
My next step will be a NDX2, then XPS DR. After that the amp upgrade would be an option. Another option would be then a new Speaker as well.
It needs a 4-pin to 4-pin interconnect to be used with a HiCap I recall. Mine was kindly included when I bought the HiCap second hand; I don’t know if a new one comes with it to not.
A Hicap comes with a Snaic5. You’d need a Snaic4 to connect a Hicap to a SN used as a power amp. If the SN is later replaced by a 250, the latter comes with the necessary lead, making the Snaic4 surplus to requirements. This can be avoided by going from SN/HC to 282/HC/250 directly.
It’s an Isol-8 Integra Subsation, it has two high power sockets and four low/mid power sockets, I also use Isol-8 wave plus power cables. Makes a significant improvement on detail, clarity and separation on my system/mains supply. Very happy I found found it with the help of a demo by my friendly Naim dealer.