While I have a soft spot for the Model G--aqua or tan--I'd have to say a Convertible would likely outperform it (depending on its condition).
Contrary to collectors' sentiment, the Model G is not the best tank cleaner Electrolux Corporation ever made; but one of the best. I read some comments of a son of Dennis McKee, a former EC & later Consolidated Foods prez, who stated that the Super J 1401 and its early successors (Olympia One 1401/1401-B/1505 and Silverado 1505) were superior to the Model G in performance.
The Model G was made to a price point, too, as evidenced by the cheaper plastic wheels, exhaust diffuser, & pn wand, and the round plug (with the stopper). To me, price point became a more prominent consideration for EC when the Model E was introduced. It was the first not to have a covering on the body, and it fell over easily and had to be retrofitted with a stabilizer (not an oversight, but a way to trim costs until customers complained). If I recall correctly, the early wheels didn't fare as well, either, and had to be redesigned.
Model Gs are easily available online, and they can still be found--albeit not as frequently--in secondhand stores. The Convertible, though, may be harder to obtain depending on the model.