I've owned both machines as well, a newer gravely would probably be my ultimate machine, but this old L8 I have is pretty decent... I liked the steering brakes on the BCS, and the BCS was lighter to use... I liked the way the bush hog was built on the BCS with swing away blades like a real bush hog. Using the Gravely though, I can tell it is a much more robust machine, it's been around for over 50 years and is still working like a champ. The Tiller on the BCS wouldn't even be fair to compare to the tiller on a gravely, lets just say that based on tiller attachment alone, bcs would win hands down... BUT, bring out the rotary plow, and I go back to liking the gravely more because of its weight. Honestly though, I prefer my old troy bilt 4 speed horse for just tilling/cultivating although there are very few times that the ultra slow speed of the BCS came in handy, it was rare enough that I don't miss it... My biggest complaint about the bcs as opposed to the gravely though was cost to maintain, and cost/availability of attachments... Finding BCS attachments floating around for sale by themselves seems harder to do than finding old gravely implements... BUT, I suspect that will eventually change as they get older and more of them break beyond repair... I like the honda engine on a BCS (had an ACME too, parts were a nightmare), but you can repower a gravely with a big honda (not exactly cheap, but would be worth it)...
so, all in all, when the engine conks out on my L8, if I haven't replaced it with a more modern gravely with steering axles by then, I'll be putting a honda engine on it and in my opinion will be a truly top notch machine... However, I mainly use mine for only bush hogging in areas my tractor can't/shouldn't go... I thought about a DR mower, but kept having nightmares of when I first started the farm and used lighter duty equipment and broke it constantly...