Tarantino somewhat recently said he is a Roger Moore fan but not much of a Roger Moore as Bond fan because he thinks Moore was too old for the role, but he would've liked to see him star in OHMSS. That is all I have to add right now.
Hmm, the more I think about that idea, the less I like it. For one thing, one of Lazenby’s assets was his physical presence and prowess in the fight and action scenes. Moore was considerably less adept in them, IMHO. It’s also hard to see Moore’s Bond playing the romance as straight as George did, though he might have handled the final scene nicely. I think he’d have had fun with the Sir Hilary stuff but those bits are silly enough anyway.
Really, of all the other (than GL)
Bond actors, Roger is the I would least like to see in OHMSS.