2 iPhones 1 SIM - potential issues?

[funinhounslow]

I am considering purchasing an iPhone 7+ to replace my trusty 5S which is starting to show its age.

However there are times when I will still want to use the 5S - trips on the bike or nights out etc.

Will there be any issue with swapping the SIM back and forth between the 2 phones as I see fit? The only issue I can foresee is text messages spread across the 2 phones depending which had the SIM in when the text was received- but am I overlooking anything?

I assume iMessages and WhatsApps will be synced between the phones - is this correct?

Thanks in advance for your help