you said in the OP you can easily use 1tb. as already stated, 1tb of internal ssd is better than 512 + external. and you said you can afford it. what more justification do you need? if max speed doesn't matter to you then get 512 and an external drive. if it does, get 1tb.
Two things to consider.But on the other hand, I can solve it using external drives.
Same with me. 512GB was enough for me to store everything important on the drive. With a 1TB I'd still have to put some data on an external drive and you need a backup anyway so, I could not justify the price for the 1TB internally. 256GB would not be enough for me but 1TB is just not worth the money for me.
Realistically most people aren't going to do that though so it isn't really much of an option.You can still sell the MBP and in theory the blade ssds should be easily swappable. It isn't integrated into the logic board like RAM.
Agreed, I've got the 1TB as well. It's a lot faster then the 512GB. If you can afford it, go for it, it's faster (way, way faster than an external) and more convenient.