I had a RadioShack meter and it read same as my dosy. average power yes, it will be pretty accurate but peak power won't even be close. Bird watts are true watts not happy watts like all the hobby meters.
I have owned 2 Bird 43P meters and they showed more peak watts than a Dosy. Reading average watts the Bird 43 is the cream of the crop, but on peak....NO.
BBI gets silly watts from his amps using a Bird 43P.