I've done a ton of research on Google and the threads here to buy a new audio interface and I'm thinking about settling for a used Focusrite Saffire 6 or 2i2 on ebay depending on the price I can get. However, I'm reading on the internet that people have problems with DI guitars clipping even when the gain knob is turned all the way down. My budget is super tight right now. $150 at the most for right now. I have a job, but money just needs to go to other things. So maybe if I wait 6 months, $200-$250. I really don't want to have to fork out extra just for a low budget DI Box.

Are there any other audio interfaces in this price range that have very few features just for recording guitar but are high quality and reliable? (My expectations are to be able to put a recording out of this quality: https://www.youtube.com/watch?v=x60G9C09UnE)

How much of an improvement in tone would I notice compared to the Stealthplug interface I'm using now?
I just bought the Saffire 56 Pro and so far I'm pretty impressed. I havent used the 6, or the interface you're using currently, but I would imagine the saffire 6's pres are the same as the class A's in the 56's channels 3-8 and they sound pretty good for DI. But at the end of the day, my take on amp sims has always been that its more about the sim than the DI. If tone is an issue, buy a decent microphone.