Would 16" be much more useful as a third monitor than 14"?

Hi!

I'm currently using a 2017 27" iMac for software development,

and I'm thinking of buying a new Macbook (m1pro 32gb 1TB).

Like many people, I'm having a hard time between 14" and 16".

In my situation it's too hard to decision.

- 16" is quite heavy, but I'll probably use it 95-98% of the time in my house.

- 16" has a big screen, but most of the time it will be paired with two external monitors (one apple studio display, one dell ultrasharp 27" 4k).

When the studio display arrives, I'm thinking of placing my dell monitor vertically next to the studio display.

And I plan to put my MacBook under the studio display and use it with my mechanical keyboard.

I want to use my MacBook screen as a third screen (email or calendar or notion...), but I wonder if the 16" will be much better than the 14" in this case.

Everyone knows that the 16" has a bigger display, but I think the usefulness of that larger display will diminish if I connect to external monitors a lot of the time.

As I said above, I rarely take my MacBook out of the house, and I use it mostly on my desk, but while using the iMac, I sometimes want to use it in bed or on the sofa.

So I'm going to buy a 14" because it's lighter and easier to move even around the house,
and for me, 14" looks better.
But when people say how cool a 16" display is, I'd like to buy the 16".

Unfortunately, I don't have the option to buy both..

There is a way to try both and return the one of them, but it is a difficult due to the current MBP delivery situation.

As I was writing this post, I thought that I could use mac studio for desk and IPP or MBA for bed or sofa.

In this case I don't have to worry about my MacBook's battery always charging, but I'd lose one great monitor.

It's a very difficult time for me, who has a decision problem.

Please help me with your experience and advice.