Because I'm in Europe, and we are all metric, I'm obviously not going to vote on this, but I'd like to pass a few comments if I may.....
To make use of these metric bits you will also need metric guide bushings. I have two options for you to consider:
1. Trend Euro style guide bushings in heavy duty plastic or steel which require the Trend UniBase for mounting to your router. These attach with two screws.
Many deWalt routers already support this style of guide bush directly in the base without the need of an adaptor plate, which is in fact the old Elu MOF96 standard:
The routers which take this type of bushing includes the deWalt DW613/DW614/DW615, Trend T5 and older 1/4in (8mm) Elus. Trend's range
includes 10, 11, 12, 14, 16, 17, 18, 20, 22, 24, 26, 27, 28, 30, 32 and 40mm (in metric) as well as a number of inch equivalent sizes including 7.93mm (5/16in), 9.5mm (3/8in), 15.8mm (5/8in), 22.2mm (7/8in), 25.4mm (1in) and 31.8mm (1-1/4in). This compares very favourably against deWalt's own range of 17, 24, 27 and 30mm. I believe that Trend do stock the plastic metric guide bush sets
in the USA (10 to 32mm in 2mm increments - and quite reasonably priced here if you take into account that price including 20% sales tax), but not the steel ones. These plastic bushings also come in a selection of inch sizes, too.
The DeWalt DW624/DW625 and Trend T10/T11 (in Europe) are supplied with a conversion plate (#DE625T10 in the UK) to allow the use of the Elu/Trend type of bush directly on the router without the need for an adaptor plate:
Trend also sell a version of this
deWalt DW621/DW622/DW626 routers work with a different (cast) guide bush system directkly in the base (without adfaptor plate), like these:
In the EU we can obtain this type in 14, 16, 17, 18, 20, 24, 26, 27, 30 and 40mm sizes from DW for the DW621/622/262 routers. They are not compatible with the Elu/Trend-style guide bush, but being of larger diameter and having a somewhat thicker mounting ring (base ring) it should be possible to machine-up a simple adaptor plate to sit in the base of a DW621/622/626 to take the Elu/Trend-type guide bush
Festool and Bosch
also have their own ranges of metric guide bushes which work directly in the base of the router (Festool actually have three ranges!). Both manufacturers sell 17, 24, 27 and 30mm bushes for all of their plunge routers. Makita seem to have have 17, 30 and (some) 40mm guide bushes available for their routers, but the guide bushes are apparently incompatible with other makes as far as I can tell
This is a brief synopsis of what we can get here "off the shelf"
in Europe. Good luck in persuing manufacturers to manufacture/distribute the same in the USA