The size of the lawn and the type of mowing is what you need to take into consideration when contemplating a self-propelled, big open spaces where you do long runs is where you get the most benefit from a self-propelled mower but as you get down to smaller lawns with lots of obstacles the benefit decreases down to small pokey lawns where a normal lawn mower is actually easier, this comes down to the greater weight & size of a self-propelled decreasing the maneuverability.
The Honda's of years gone by have had a great reputation and been the go to for most commercial guys, whilst they are still pretty much the go to mower the "novel ideas" you mention in general have seen a lot of operators go from raving about them to begrudgingly still using them, a lot of this was the newer designs inability to deal with wet grass which probably won't be as big of a deal to you as a commercial operator but other common gripes are the price premium, not being as robust as they used to be and the cost of parts. The motors are still great though. (I however, haven't really looked into any new models in the last year or two, so may have improved a bit.) I personally wouldn't worry about a key start, the Honda's are an easy one pull start and a key start on them is a bit of a case of adding complexity to solve a bit of a non-issue due to their ease of start. They are still a good mower and will likely last you a very long time but the question of if they are being worth the premium they charge is probably the bigger question.
Another that is a favorite with the commercial guys is the Rover Pro 560 and 50, I have the 560 which I got crazily cheap and has a very good reputation, its more of a basic but proven design. I have had a few problems with the drive system on mine but I am the only one I have talked to that has and wonder if it has more to do with not being treated properly by staff than quality issues, the upside is the design is simple and the parts are comparatively cheap. It's sold with different engines, mine is the 910 which is a Chinese engine that people said to be wary of but it has been bullet proof. however requires quite a hard pull to start so I wouldn't recommend it for the wife but it can also come with a Kohler which should be better.
If you want to do a bucket load of reading have a look at the indmowing forum, it's to lawnmowers what myswag is to camper trailers. The thread on the ProCut 560 is 70 pages long for example.
