Here's my take: Big, exotic moto, you tend to ride on the tarmac and do big miles. You're perceived as a rich gringo on a big, expensive moto. Exotic moto; difficult to find parts in many parts of the world. Detours, flooding, landslide, mud, soft sand; all are a bigger problem on a heavy moto.

Small moto, more exploring and spontaneous off the beaten track decisions; meaning more adventure and interesting experiences. Easier to handle on bad road conditions, nimble when you unexpectedly meet that fast moving car on a single lane mountain road, and easier to pick up when you tip over. Often a smaller moto means you're riding something similar to what the locals are riding. You're still perceived as a rich gringo, because you can afford to travel internationally, but you also are riding something locals can relate to. Less expensive to repair and better gas economy. Much easier to access secure parking at night.

Yes, where traffic is very fast, a small moto puts you on secondary roads or on the shoulder. But in many countries, on good tarmac, fast means 80 - 90 kph. Normal speed on many two lane tarmac roads is 40 to 60 kph.

The choice comes down to which way your goals sway between these extremes: do the miles to accomplish your RTW trip, or meet people along the way and "smell the roses". Most important is riding something reliable and easy to repair using local resources. I don't remember anyone saying they wish they had a bigger moto on an international trip; but I do recall hearing travelers say they wish they had lighter & smaller.