Thanks for the detailed answer. I suppose tracking stages of sales pipeline is a good metric as you and several others have mentioned. Much better than being completely in dark.

Also by 'backlog', I assume you meant product backlog (e.g. features remaining) or something in the sales funnel?

While tracking the sales funnel is great to use as an indicator of progress, it is not great as a decision-making heuristic internally (e.g. for product features) as pg mentions in his essay 'Startup=Growth'. I suppose product backlog is a good metric for such cases.

Tldr; use sales funnel to track business side and feature backlog internally.

Because of the faster feedback cycles, the web/mobile app world can use the same metric to track internal and external progress.