If your hips are stranded way out over your back wheel it becomes very hard to keep your weight centred on the bike. A longer chainstay would help prop up the rear end but it wouldn’t solve the problem of your hips being miles behind your cranks.
Yes but relatively, unless you have disproportionately long/short upper/lower legs surely the position for your saddle is relatively the same?[/quote]
The saddle position is similar but if the top tube length remains constant, steepening the seat angle lengthens the reach and puts more weight on the front. On the 456 you really felt like you were riding on the fork at times to get the most out of it, on the Blue Pig this isn’t so noticeable. The reach also gives you more room to get your weight onto the front end when you’re climbing.