Mhh, i have some issues with suggestions moving in MantisBT without staying in the forum as well.
The problem with putting the suggestion in the bug tracker is that you will only find them if you search for them, which you can't if you don't know about them, and you won't know about them because theres no (to me apparent) way to for example, only display the suggestions and not bugs in the first page by default (theres a way to change columns and other things in preferences but not WHAT content is displayed in these columns...)
So this kinda removes all community involvement in suggestions.... except of course the 3 people who actually take the time to read every suggestion in that system
By Manually clicking on "category: Suggestion Type X" -> Apply Filter. And this category function + Apply Filter is extremely clunky as you can't say "want to see ALL suggestions but NOTHING else" you can only filter 1 by 1 through them.
And lastly, whats also annoying about MantisBT is that closed issues disappear from the "Monitored" and "My Issues" lists, which is evil_Bad ... because you can never again find them, which is ok for bugs that are fixed, but not for feature requests that are, for the time denied but may later come up again.
So generally, i have the feeling that moving suggestions to this tracker is going to reduce the inflow of opinions about them drastically. Which is of course, bad.
Imo the only way to make suggestions work in at least half-a-decent way is to maintain them in the forums but issue them at the same time in the tracker, then provide a link in the forum to the tracker entry, and in the tracker entry to the forum entry.