By all means shoot and hold both. I prefer the Steyr and size wise it is about equal, maybe a little smaller than the HK.
Took my dad's USP Fullsize out shooting today and I am much more accurate with the Steyr type sights than the 3 dot night sights on the USP. The USP flips like a mule and I cant hold it comfortably and high. The USP is a good gun, but it is not for me and feels like a brick in my hand compared to some other guns. I like the classic 1911 grip angle better so the HK points a little better for me. The trigger on my Steyr is about 5-6lbs, but with a clean break and SHORT reset, while the HK has a horrid trigger (yet light on my dads, around 3-4lbs in SA) and LONG reset. For the price, you cant really beat the Steyr. CDNN is running low on certain models, you can call them for availability. The Steyr is about ~$300, while the HK can run between $600-700+. Also, the Steyr has a tennifer finish ala Glock, which I prefer over HKs HE finish. You cant go wrong with either, but I would definately shoot both. Higher price doesnt always mean better gun.
You may also want to consider the Springfield XD with a Stainless Slide or a CZ75/CZ40 (prefer not to get the rust problems with the standard slide on the XD). If you are looking at USPs, im guessing you are considering more expensive firearms as well so you may want to check out some other guns too.
