For a young guy like gif4445 (I'm 73), I would have thought 11-34 with the 50-34 compact would be the first and least expensive alternative to try. That would give a 27 in low gear. He might need a long cage RD if one is not already fitted to the Roubaix. Messing about with a triple and all that that involves would be pretty expensive.

if you must have the premium level of components , probably so ..

Thanks for all the great suggestions everybody! I will confer with the LBS this coming week, with these suggestions in hand, and get a general plan just in case I need to make a change. My guess is I will need the lower gearing. I have a knee that the Ortho believes is a candidate for micro-fracture surgery. But the rehab down- time (4 months off) will do more harm than the benefits of surgery IMO. It's not too bad if I'm smart about it. And that includes no extended mashing. For now, my plan is to continue to work on my power: weigh ratio and , of course do as much hill riding locally as I can. By the end of spring I should have an idea. Then sneak out to the mountains before the first of July to see where I'm at.

I'm not being flippant when I say this: any gearing is adequate if you're willing to walk your bike up at least some hills. The question is how much will you have to walk it. The hills you expect to ride are a big factor in that. Your conditioning is another big factor. A lighter bike helps, and the Roubaix is a heck of a lot lighter than an LHT, but not enough to compensate for the very high low gear it has. I can't say whether that should matter to you.

1 - Try the current gearing and see if it works for you.
2 - If you need lower, get a 9 speed Shimano (or Microshift) RD and a 12-36 10 speed cassette. That's as low as you can get with the current crankset.
3 - If that is not enough you will need a smaller chainring which is not possible with your crankset. Either change to a triple crank, requiring a new front shifter and FD, or you could go with a MTB 2x10 crank and live with the wider Q-factor (pedal stance) or a super compact road crank like a White Industries VBC or a Sugino OX 601.

Take off components at point of sale have trade in value to the Dealer , because they are obviously new ..

so at point of sale is an excellent time to change out stock gearing.

likely a discount on the new stuff or at least a labor rate cut is possible .

better may be to know what you want ahead of time, and when the bike comes out of the shipping carton,
those components may be switched,
and the pre delivery, display floor set up and fine tuning is only done once .

If you don't want to mess with shifters and ders and other big changes associated with triple conversion, you could temporarily add the triple crank and just tweak the existing der to switch between the two inside chain rings. I'm doing the same thing on a project where I swapped the outer ring to a CF chain guard and use the remaining 42 as my top chain ring, and swapped the inner 30 down to a 26.

But I also agree you might want to try what you've got first.