I quick cross reference to GPS speed might lead you to quickly diagnose a blocked pitot tube if you're climbing. This has caught out many PPLs and even several airliners in the past. If you ASI says 130 kts and you are aiming for 100 kts and you don't spot that at this attitude it should read 70 kts, then a quick glance at the GPS which might show a slow GS could make one realise there is an issue.
I agree that Power + Attitude should alert you but it doesn't always (apprently)...