here's my compact double built on a Sugino XD2 triple crank, guard + 42/25T
works great with an Ultegra CX70 FD and Microshift R10 RD, 12-29t 9-sp rear

here's the gear analysis
have to plug in 38mm for the tires to see the actual
The overlap fills in the gaps where the custom cassette goes wide.
But for the most part it acts like two 1x9 drivetrains (or two sequential 1x7 and splits out easily at 50")
The crank and chainline work great with a 111mm BB
well over 5000 mi on this in steep hills, and it's a joy - shifting this with index is totally mindless

Max ring size on the CX70 FD is 48T, so this FD would work great if you wanted 48/28T double

I derived the compact double from my cyclotouriste triple, half-steps plus granny 46/42/26T, wide-7 rear 12-32t
Cyclone GT RD, Shimano 600 EX FD - with a low-Q cyclotouriste triple, you use a road double FD, and hard to beat this one.
Chain wrap capacity is one link short, but never a need to cross-chain 12t in the rear with 26T in the front

Here's the gear analysis (32mm tires)
This one needs 121mm asymmetric BB (best) or 126mm symmetric.
over 10,000 mi on this setup, and it's a different joy - get into the big ring as soon as you can and use the half step first for climb

Both double FD make the wide jump with aplomb - a triple FD would just get in the way.