Using both Apps is not a problem, Inbox is like the "modern-twist" on email allowing you to easier manage task, and to an Assistant to Gmail.
How Inbox works with Gmail
Inbox was built by the Gmail team to give you a new way to stay organized and get back to what matters. Everything from Gmail (your emails, contacts, and labels) is available in Inbox. Gmail and Inbox stay in sync so what you do in one app carries over to the other. Gmail and Inbox have many of the same features, but there are differences. To get the most out of Inbox, try to use it for all your email. You can always switch to Gmail if you want to.
Source:
How Inbox works with Gmail - Inbox by Gmail Help
Source:
Get started with Inbox - Inbox by Gmail Help
A new addition for Chrome user allows them to Share or Save Links.
Download (Chrome Web Store):
Inbox by Gmail
For example, you can Save a Link to Inbox, then later you can check the link out or complete any task (ie. Vehicle Tax).