Their scans are icon based rather than language based. Takes some getting used to. You need to think about how to mix/match different alerts/filters because a slight change can make a big difference.
So the level of "customization" is contrained by the limit of the canned filter, not by your own criteria.
Quick example which Ive posted before:
You can set TI to scan for stocks when price crosses above/below its 50 or 200 day MA.
Fairly standard values.
You cannot change the criteria value. Like say Macd values 12,26. Again fairly standard but not represented.
Some things you can work around.
Like your gap request. You will get a large, probably unwatchable list of stocks if you dont set some restrictions.
You can adjust to filter by price, spread, gap % or $, volume, ATR and many others. That could be useful to you.
Or not.
I thought TI had a 7 day trial but I dont see it on their site.
There are better (more expensive) scanners out there.
I use it to find very, very specific criteria since it is one of very few scanners that can actually scan the entire market, but then fine tune those stocks with Radarscreen.
For example using unique scan to TI, I found BBD on 6/29 and EEFT on 6/28. Took a nice chunk from both. Would have never saw either without TI. But to be fair to other real time scanners with a little thinking on your part could have found em too.
I have experienced some lag and it was down once briefly. But usually it's reliable with just a slight delay (miliseconds).