I'm using IB and Tradier. For a month I had the Tradier/Tradehawk combo but didn't find the Tradehawk platform worth paying extra $50. The mobile app is useless. The desktop pp looks decent but in practice it's not better than the web interface (Dash) for my purposes. I run Tradier in a browser on my phone, more or less the same as on the desktop.
The main problem with Tradier is that I cannot see the "true" bid/ask spread when I place an order. The bid/ask spread in IB is tighter and appears to be more real. So, before I place any order with Tradier I enter it first in IB (with, say, buy $0.01 order) to be able to see the spread and the last price. Then I enter and subsequently modify the order in Tradier by consulting IB. After the order is executed, I keep the $0.01 version of this order in IB to track its performance and to have an idea at which point to close the position in Tradier.
It's a bit cumbersome but less than it appears.