yes have electric 3 yrs old & propane fueled 7 yrs old in different homes. no issues w doors (except to adapt to left closing). both perform well. electric more bells whistles being newer.. digital and pizza stone. however on advice on tech (we had 1 svc call for faulty thermostat ez repair but they pulled entire panel and replaced), pizza stone carefully removed, stored. this way oven heats and cools faster. note that neither throws excessive heat into space. trade off is a fan running to aid slow deliberate cool down. this might annoy in an open space eat in kitchen. our fan friendly oven is installed in walk in pantry utility room that houses freezer and extra refrig (main kitchen has 30" Leibherr)

Like any ovens there are features on each one that might make a difference to him. One thing to look at first is the size of the racks. How big of space will he need? I think that the BS holds a full commercial sheet. Read he manuals very carefully to see how these ovens work. If there is anyway you can see these live and bake in them do it. BlueStar electric https://www.bluestarcooking.com/wp-content/uploads/2015/12/BlueStar-EWO-Use-Care-Manual-750162-8-11-17-Merged.pdf The BS has a baking stone in the bottom and the oven cannot be used without it. This will add to the preheat time. They have intensified the preheat so they warn against putting any food in until it is preheated. I would never do any baking until an oven is preheated and stabilized but sometimes I put casseroles or something else in when I start the oven. This is from the manual. Everytime the heating elements come on, the convection fan comes on. You can never shut it off completely. Gaggenau is a very different oven. This is a video showing how to use it. https://youtu.be/IEjZViE4hig Gaggenau 400 https://media3.gaggenau.com/Documents/9000866756_K.pdf Gaggenau does recommend convection for cakes but I am not a fan of using it for cakes unless that is what you are already using and you have recipes that work. The convection changes the direction of heat coming to the cake. It is also superficially drying to the cake so inhibits starch gelatinization. Most cake recipes were developed with heat coming from the bottom. They talk about using convection first and then if it is getting too done turn it off. I do just the opposite. Standard bake then add convection after the cake rises if I want more browning. The video also says that convection keeps moisture in. No it does not. Some people might get that idea because the faster browning you have with more air movement makes things look done before they are over cooked on the inside. The Gaggenau also has 4 elements. It has a hidden top element as well as a broil element. The Gaggenau has a steep learning curve. See page 11,12 for all of the modes it has. I would also look at some of the portable commercial deck ovens. Some people put them on a cart.

The LG LWS3063ST ($1619) is Consumer Reports's top-rated wall oven. The upscale LG Studio LSWS307ST ($2114) is similar and has a different appearance. Both are far less expensive than that Bluestar oven ($4400+).

I have no advice but have heard about the noisy fan as well. Seems it goes on the minute you turn the oven on, until it gets below 200 - I may be looking elsewhere as I don't have gas in my area.