So I did some informal testing, with probably a large margin of error, I have some pictographical results.
I picked Blitzcrank, because I own him(it?) and he has a base 300 ms. 8 Seconds of walking down the bottom lane put me a little ways behind of the inhibitor.
Purchasing boots of speed boosted him up to 350 ms, and 8 seconds brought him past the inhibitor, put not yet past the inhibitor turret.
I attempted to record results for 406 and 455 (like I said, it's hard to get the higher numbers precisely) but botched the results, and in each case I was only about the same spot as 350 ms.
Finally, I bought Phantom Dancer and Boots 5, hit ghost (un-talented, sadly) and activated rank-5 overdrive to see how far I could get when speed was pushed to egregious levels. Since Overdrive lasts for 8 seconds, it made for a far more accurate timestop. I made it here.
So we can safely conclude that, unless you're backed in to your own base, it is always faster to recall.
Now if you'll excuse me, I'm going to go avenge my horrendous 6 - 4
previous test game. I will get Ashe Bot this time. grumble grumble
Anivia and nautilus perhaps? Should work pretty well.
Anivia provides with a lot of utility and CC, meaning the AD will have time to damage the opponents and be safe, Nautilus is very tanky and filled with CC to protect the AD's, combined with Kayles ult you have one unreachable AD.
When late game comes and your ADs start to hurt, all you want to do is to give them time and space to damage the opponents, and you want them to live, so Nautilus provides 4 CCs and Anivia is like heaven for an AD, she can split a team up with a wall, slow an entire team and stun. This makes it really hard for the enemies to reach you, and even if they do, you have Kayle ulti to save you.
Best Answer
There is no "penalty for surrendering," but IP gain is linear with time (up to a threshold: 55 minutes), so the longer you stay (even if you're losing) the more you can gain.
That said, it is often faster to gain IP by surrendering if you believe you have a good chance for winning (eg. 50%)
btw: CITATION