I'm making two different cakes for a Halloween party where the client will be using the same large flower for each cake and changing out the cake for different photo ops, etc.  I would like to make a less delicate flower than one made from gumpaste to reduce the chance of being broken when moved around.  Do you think using Wilton fondant with some tylose in it would do the trick?

I would use gumpaste, but just make it thicker so it will hold up to moving around. You should probably tell your client you cannot guarantee the flower's integrity when it gets moved around several times to several different cakes. I would tell her the flower is as fragile as thin glass. If it gets bumped around, it may break. Perhaps she would want to pay for a few flowers just in case the original one does break. 

I'd use 50/50 Wilton fondant and gumpaste. It's still risky, though, to be moving a sugar flower. Is she really saving that much money by having just the one?

I'm making two anyway, *just in case* - so perhaps I'll offer up the 2nd to her if she discovers that she needs it.  Part of the reason that I was hoping to use this Wilton stuff is because she wants a black flower - and I was hoping to avoid the task of dyeing, dyeing, dyeing, until I got black.  I'm about 3/4 of the way through with one and it is actually turing out great.  :) 

Black - Then I'd go with the 50/50 gum paste/fondant and you can add tylose if needed.  You can still dust with black if needed.

Ok - having never used Wilton fondant before I had no idea what to expect....but with a little bit of tylose added in, this stuff dries HARD and I was able to roll it pretty dang thin too.  I'm going to dust these babies with some black petal dust and call them "done"!

I'm glad it worked out  :)

I was going to recommend Mexican Paste that is found at Global Sugar Art. I got it for my lace molds and it is so strong that I tried it on roses and it worked wonderfully. It is pure white and dries very strong. It can be made and stored in the freezer and it works exactly as promised.

This was one of two roses I made for two coordinating cakes - the Wilton Fondant, with some tylose kneaded in, worked great.  I was even able to "patch" a petal that I broke using some fondant glue and it dried nice and hard within 24 hours.

very nice cake! I love it!