Lucy,

I own 5 routers and have used others. I don't think you will notice any big difference between the DW621 and the ones you have. There are little things you would like better about one versus the other but the motor size is about the same, both have at least decent collets and both have decent ways to adjust depth. That is what a router does. I've never used a Festool anything and I may never but the Domino interests me. If I was to drink the green cool aid, it wouldn't start with a router. There are lots of pretty good ones that cost a whole lot less than a Festool.

But if you are willing to change bits, you can do your roughing cuts with a router bit that isn't real sharp. At most you make an additional pass and smaller bites. Then use a really sharp and clean one for the final pass. That would help on bits. I hate throwing them out too. Routers all dull bits at about the same rate.

You don't need spiral upcut bits for this. But if you use regular straight bits, you want one with a bottom cutter. It will make holes much better. At least for the roughing cut you need to be able to make a hole. A single flute bit takes half as many cuts and dulls twice as fast as a two flute bit. I have some but I am no fan of them.

A 1/2 shank will greatly minimize any slipping in the collet but I don't remember you mentioning that as an issue. A whiteside wouldn't break at the transition between the 1/2 shank and the 1/4 cutter but I've had cheaper brands break there. A 1/2 diameter straight bit is more robust and could fit with a plan to go to a 15A router but I don't see why that would fit your situation.

I think you just need a new template guide and maybe some straight bits with bottom cutters. I like CMT bits, I hear Freud are good, and I like Whiteside. I am not sure if I would trust them for a 1/2 shank necked to a 1/4 cutter but I use a lot of MLCS bits. A 1/4 shank 1/4 cutter bit would be fine from MLCS. I think you said you need to keep the cutter the same size to keep from a major project on your templates and I see no reason to embark on that project.

But two routers is not overkill in my book. I like the interchangability of having two PC 690s. I have four bases for them and like just moving motors. But for your situation, you could have a roughing setup and a finish setup if you had two routers. I also have a bigger and a smaller router and a couple junk routers.