I can't speak from personal experience, but I think I have the next best thing in that I personally know people who have gone out and delivered the Samaritans Purse shoeboxes.
They are adamant that there is no real evangelising, other than the shoebox itself and the love that has gone into that. Some people have said no literature at all was given out, and definitely no talk, so I don't know if that is now standard procedure or whether these were just in non-Christian countries. Others have said literature was available - not put into boxes and no-one even pressured to take them, but they were just 'there' on a table. I have absolutely no reason not to believe these people, they are all very 'aware' people who question things and wouldn't go blindly into anything like this and don't accept anything just because it's under a Christian banner. So that's what I have to base my decision on.
I think people need to find something they are comfortable with. I personally do the Christmas shoeboxes and have found it very useful with my children. The fact that we have to put in such basics as toothpaste and soap is an eye-opener to many people and does make them question what we have and what others lack.
However, I also take on board the point that our money can also be used in other, perhaps more 'effective' ways, and that's why as a family we donate to many other charities including Oxfam, Christian Aid, Plan etc. I think people need to be comfortable with the charities they donate to, and someone finding an alternative charity would be fine by me. As far as Samaritans Purse goes, I think perhaps it should be pointed out that the boxes are just one very visible area of what they do, they are also involved in long-term projects such as bringing better sanitation to villages, emergency relief, community development and medical programmes including HIV prevention/care. Of course the shoeboxes get more media attention and are liked by families and schools.
To the original poster, I don't think it's any less personal just to take in an item or two. Some people find the idea of doing a whole shoebox daunting. Our school does both - children are encouraged to fill a shoebox and take it in, but each class also does a class box, so you can take in just a bar of soap or just a small toy or whatever.