I only went road in 2006 and up till then I was riding MTB's with 44/32/22 and 11/32 gearing. I used those bikes on Metrics and Century rides with slicks fitted as the only mod. I even did local rides on the road with them with Knobblies on and I do have a marker hill that I still use to gauge performance. That marker hill was not easy on the MTB and I did use 22/32 at some point on the hill. First road bike and I got a triple--52/42/30 and 12/26 cassette. That hill was hard on the road bike- but no harder but was quicker. Later on I got a Compact Double with 50/34 crank and 12/27 gearing. Still hard but no harder than the triple or the MTB but a lot quicker.

With gearing being higher on the road bikes- You are tempted to think that hills would be harder. They are not-Or need not be. The bikes are more suited for the road and work better on the black stuff. Gearing can easily be changed and if you have mountains then I would suggest a triple and the you can get the 1 to 1 ratio on them by fitting a 12/30 cassette. Even compact doubles can get lower gearing than you would ever need (Unless it is mountains again) by fitting the 12/30 cassette. The big problem in changing to a road bike is fear. My fear led me to a Triple crank and is the way to start if you have hills. But a bit of training and a compact double will suffice for most--Especially with that 30t ring on the cassette.