I just like the pliability of the heating pad. If I want it draped over the top, it drapes. If I put it inside the frame and secure with bungee cords, it holds the shape of the frame. For me the idea behind MHP is to keep it simple and inexpensive. I was going to switch from heat lamps to an Eco Brooder. But it was just too expensive, and it didn't give me what I was looking for - a cozy, dark, almost enclosed soft place for them to sleep, warm up, and hide if they were spooked. After I found Patrice Lopatin's video of chicks ducking into their little cave and then found Bee's heating pad brooder, I was sold. After using it with amazing success for 6 batches of chicks, I will never go back to anything else.
Through the life of this thread, it's been interesting to see the modifications and changes that folks have tried. Some of them didn't make much sense and kinda defeated the overall goal of MHP. Some of them over-complicated a very straight forward and simple method. Some were excellent and well worth looking into further and/or changing to, and some were so clever and simple it was a head slap moment - "Doggone it, why didn't I think of that??" Strapping the pad under the frame and portal doors in the outdoor brooder are two that come to mind immediately.
These "commercial" animal heating pads have come up here from time to time before, and the reasons for people deciding against them have pretty much been the same. As for how much electricity MHP uses, I guess I fall into the "I'm not that nit-picky" category. I'm not worried about a little watt here and a little watt there. They cost less to operate than a heat lamp, they are safer than a heat lamp, they offer my chicks a full day/night cycle from day one, they are easy to wash, roll and store. The chicks determine their comfort level and security. And with just a bit of scrap fencing, a few bungee cords, and a heating pad, I can raise chicks that are healthy, calm, confident, and feather out faster without a lot of hand-wringing and overthinking on my part. And I can use the pad for other things when it's not being used for chicks so it's multi-purpose.
Even with all the modifications and individual changes (depending on people's comfort zones and situations), keeping it all as simple and inexpensive as possible is the ultimate goal with MHP.