Should an MTB saddle be lower than a road bike's?

I'm not much of a mountain biker (in fact, my newly resurrected low geared Viscount is my mountain climber). However, an early MTB item called a Hite Rite sounds like a lower-cost answer for you. This device was an external spring that clamped to the seat post. Set it up at "normal height" and when you want it low, active the seat post quick release and your body weight causes the seat to drop. Re-clamp the quick release and the seat stays down. When you want it at normal, remove your weight from the seat and up it pops. Here's one on US eBay, not exactly cheap but it has the make-an-offer. Sometimes, used ones pop up.

www.ebay.com/itm/Breeze-Angell-Hite-Rite-Black-Mountain-Bike-Seat-Height-Adjuster-Dropper-Post/122804439043?hash=item1c97b70803:g:W5UAAOSwlEdZrJ6i

Best,
john "wheelson"