While I know that tip-n-dip systems are not overly popular in the us or the uk, they are successful here in Quebec.
Here in Montreal, there are a great many technicians that do ONLY tip-n-dip (known as gel-resine, here).
No, they are not the strongest of systems. They require frequent soak offs to start afresh.
I used a system by "France Lecuyer".
BUT there are people who prefer this to L&P or UV Gel, and get on very well with it. My aunt is such a person. There are many others.
It's definately worth considering, to add as an additional service.
While I do mainly UV Gel, I do have 3 clients that prefer tip-n-dip, and they have been wearing it for years. They prefer it. It's 'thinner". Also qiucker to apply and/or fill.
It's most suitable for those that aren't hard on their hands and prefer something that will only add a little strength.
I wore it for 10yrs, myself.
If youi've any more questions, just give me a holler.
hth's