I think they're both quite capable managers at this level.
If you look at the club's strategy we aren't desperately trying to get out of this league like some other clubs we're up against. I won't get into whether it's the right strategy or not, but ours seems to be to get closer to financial break-even by treating players as assets - hire younger players with a lot of potential, and develop them so the club's networth rises with them.
Financially speaking that's the only way to get even close to break-even in this league so there's some merit to it.
As a coach, IB has proven himself more than capable of implementing that strategy, and based on the players we have, the strategy seems to be working, at least to an extent.
As a football club through, it means we will likely see the playoffs but in any given year (especially the first full season that strategy is in play), we're unlikely to go up. Not while there's teams spending hand over fist to get promoted above us. Still, there's a bunch of random that goes into any football match, and the fact is if you keep making the playoffs, sooner or later you will go up.
All of that said, there will be years where that strategy means we're really strong. I mean we're hiring kids whose potential exceeds this league, so if we have enough of those in the squad at the right point in their development, we'll be very strong. I don't think we're quite there this year.
The financial numbers look a lot better in league 2, and better still in league 1 etc. So it's all tradeoffs. Plenty of clubs seem to go bust chasing promotion with silly money though.
I don't want to re-litigate the debate, but I think judging Ardley by the relegation year is misleading, and I'm not at all surprised by how sillyhill's done under his leadership. But IB is probably a better fit for the club's current strategy.