Moyles's last show will air on Friday, September 14 with a week's gap before Grimshaw takes over on Monday, September 24.
"I think Grimmy's going to do a brilliant job on the Breakfast Show," Radio 1 specialist new music DJ Stephens told Digital Spy.
"I think he's going to be really exciting. I'm going to be listening, definitely."
When it was suggested that Grimshaw is a bigger fan of music than Moyles, he replied: "I think everyone likes music in a different way.
"Some people are quite laid back about it, some people are really hungry for it. I think Moyles likes music, but I think Grimmy likes it in a different way."
Asked why radio and Radio 1 have remained so popular in an age of free streaming music, Stephens said: "It's to do with DJs, but it's also to do with music choice and selection. People trust Radio 1, because of the track record.
"People like having music guides to guide them through all the music that's out there. It's a trusted source to support new music - that's part of what makes the music scene so strong in Britain."
Stephens is currently supporting the O2 Think Big Build-a-Band project, which is open to any vocalist or instrumentalist, DJ or MC between the ages of 16-25.
To be in with a chance of becoming part of the grassroots Think Big band, Stephens is asking young people to send an audition video via the O2 Think Big website by September 13.