[JIMMIEM]

I've had one of these for close to 20 years. I am a diyer so it doesn't get used every day. Part of the speed control system is a Magnet Ring. My Magnet Ring broke recently so I started looking into reviews, as you are doing. One comment I found was that using this router in a table was not a good idea due to the direction of air flow which would result in a dust build-up inside the router. I'm not sure if this would contribute/cause the speed problem. When I opened my router to replace the Magnet Ring it was pretty dust free. I do vacuum it every time I use it. I have a dust collector hooked up to the fence on my router table. Based on my experience I will continue to use my router in the table.
When I have seen comments on Speed Control problems the first response seems to be the Speed Control Unit. I haven't found a lot of info on the Magnet Ring so I'm wondering if some responders don't know about it.
I've contacted DeWalt on several occasions and the reps don't provide much info. They usually say to contact an authorized repair center.

 

[JIMMIEM]

I'm wondering what model you have. Have they been making the 618 that long? You'd think they would have tweaked some things if they had users complaining about a consistent defect. Although, 20 yrs out of your router is pretty good.

I have the DW618. I haven't seen a lot of comments. I saw a recent post/comment and asked the poster where he found the info. He only referred to a couple of sources. 20 years as a diyer probably doesn't compare to a daily user. FWIW it was fairly easy to replace the Magnet Ring and the shipping was more $ than the actual part ($2.99). I don't know how much a speed control unit would cost but it looked like an easy DIY repair.
From the comments I have seen a lot of folks use the DW618 in a router table.
I've got the 3 base kit (fixed, plunge, and D handle) and have used all 3. I have an extra fixed base and leave it installed in my table.
The only other routers I have used are an old Craftsman and a new Makita Compact so I can't comment on other brands in the DW618 (midsized) class. If necessary, I would buy the DW618 again.