Loss rates were one reason why the Halifax wasn't so highly regarded at the time. These days we tend to look at it with rose-tinted glasses because of its war effort, which was, undoubtedly substantial and important, but it gained success despite itself. The early Merlin engined Halis had numerous issues and the type became known for high losses on ops, not just to enemy action, either. The most serious fault was rudder overbalance, which knocked the aircraft into an irrecoverable dive and was not cured until the B.II Series IA with its bigger D-shaped vertical stabilisers in late 1942/early 1943. These were fitted to subsequent marks and cured the overbalance. The good performance and reliability of the Lancaster I when it entered service didn't help perceptions of the Halifax either.
Once the Hali III entered service it had marginally superior performance to the Lanc I, but the Lanc III could outperform it in terms of cruise speed, altitude, range with a heavy load and it could carry a greater tonnage of bombs, and a greater variety of them. In favour of the Halifax is that it was arguably more survivable than the Lancaster, and supporters state this as a benefit, but the reality was that Halifaxes suffered higher losses operationally than Lancasters and were more likely to crash.
Harris' disregard for the Halifax was well known and while the Hali III redressed the balance a little, it came along just as Lancaster production numbers were increasing and Merlin Halifax units often replaced theirs with Lancs.
Anyway, back to Blenheims.