It makes no difference what kind, or size, supply line you use. That water only refills the tank. The water IN the tank does the flushing, not the water coming through the supply line.
Thanks all. I guess you can tell I'm pretty new to this toilet
business. I ended up getting one of these. I hope it'll do.
The shutoff is a floor mount. I screwed up when I ordered
the Drake toilet. I thought I had ordered the SL version
which is a 16.5 height bowl. I ended up with the S version
which is 14 5/8". To send it back is too cost restrictive for
me right now. Is this 20" going to be too long ? I bought
it think I was getting the 16.5 version bowl at the time..
If you really want the ADA model, you could probably sell the one you have for close to what you paid for it. ADA height is great for any one getting to an age where the knees don't life as well as before and for anyone of medium height like 5'8" and up. Kids and petite folks would probably prefer the standard size.