Jeff,
Flex track disappears on most buildings, I have very high end clients that have been thrilled with the lack of being able to see it.
The other thing many historical and old buildings use is bird wire, it is one of few deterrents allowed by historical societies. I'm
working on some bids right now, will pm you with some more thoughts, I don't do tons of bird work by any means, but I've used
all of the products available and have seen how they look, how clients like them and how they are to install as well.
While there are folks who use the gel, out in my climate that gel always turns into a black sticky feather and dropping covered mess,
if they don't like the idea of seeing the deterrent, they are not going to be pleased in my humble opinion, when their nice old buildings
ledges turn into a tar pit. There are gels that say they stay clear and don't turn into that, but that has not been my experience following
behind others who did that first. Most often this is a go to for pest control operators in my area when spikes aren't desired or wanted.
The other question to ask yourself is would you rather attempt to sell a job that may be $15-$20K for solid exclusion work, or have a
monthly check for trapping that might run $300-$500 or less depending on their willingness to pay.
I always go for the exclusion, I can sell it, people understand the benefit and I have solved their problem, no more birds, no more droppings
and they should know you did that and everyone who works there and has stepped in pigeon droppings, looked at them out their windows
etc...
Could be a big new market if you aren't already doing much of that work.
Let me know if you want to discuss more, be glad to help you out.
Justin