I use Saito 60T flat twin and 100Ti inline twin.
Both engines have single carb and they both run very fine without
any glow driver, 100Ti is mounted inverted.
I was impressed with their twin cylinder engines.
Although multi-cylinder engines are weaker on power and heavier
on weight than the same displacement single ones, they fit nice to
some specific scale models on sound and appearance.
I don't have any experience of twin carb and bigger twins, but my
buddy uses Saito 270T which has twin carb and runs very very well.

Tsutomu Mabuchi