Old compression fittings - leave well alone?

[BillyWillySilly]

I've been diagnosing some heating problems and found that we had 5 radiators coming off a 15mm feed, part of which was setup in a series. No wonder the last two didn't get hot. We will soon be dot and dabbing over a wall where some of these pipes come down, and I have decided to cut the series out of the loop as we don't need one of the rads and the other can be fed from another set of tails.

Here's the junction (right term?):

The left is the hot feed which I am going to join directly using a new piece of copper. The right has a lovely compression fitting that I think is a repair. Looks like some solder in there.

Question is, should I leave this compression fitting alone considering this is going behind plaster in the future?

Also, I've unearthed 8mm microbore with compression end caps (this is the same room I have another thread on here looking at the plumbing. No idea if they are connected at the other end but there's been a fair bit of work done in here over the years.

You can see that I've exposed most of the pipe run so I could solder end caps near the door where the other pipe work runs form the boiler. We haven't has problems yet and this appears dry so far.

And yes. I know about the damned artexing. Why do you think we're dot and dabbing it?

 

[Lower]

Quite simply, no. I would replace the compression fitting with a proper soldered joint. You don't want it to start leaking in the future when its buried in a wall and the solder around the fitting makes it look very dodgy.