I've pre-germinated seed of melons, cucs, and peas with good results. On moist paper towels in a plastic bag for just a couple days at room temp. Be sure to check them every day...if the radicle gets too long, the seeds are very difficult to handle and are fragile. I normally plant when the radicle has emerged just 1/16" or so.

One year I noticed my pre-sprouted peas, right next to the direct seeded ones, were slower to grow, for a good part of the season. Made me think there must be components in the soil connected to germination and early growth. I see others' experience has been different, however.

Since that experience, I stopped pre-sprouting. I will be curious to hear of others' experience.

I've compared soaked and unsoaked pea seeds, and the unsoaked ones came up first (in warm, fall soil). I think of pre-sprouting as a way to increase success if you have challenges like heavy, cold soil or corn seed maggots which could endanger survival of certain seeds.

With melons and cukes, I like to start as transplants if seed is an expensive type (or has been take off the market, like my favorite), using a light soil mix and Root Trainers. I plant the seedlings as soon as the seed leaves open, using a plastic knife to slide the rootball out of the open container onto my hand and then into the ground. No setting up lights, etc. because the plants are outside in the sun during the day for a day or two only before they are planted.

Here is a link that might be useful: root trainers

I think hepatica_z7 is onto the right approach, plant the presprouted and the unsprouted seed side by side and observe for a season.

Controlled experiments has been a lifelong hobby of mine and I have found very little benefit, if any, to presprouting. My few experiments with presprouting were mostly with flowers but the side by side controls should work for vegetables too.

However, I have had good results with soaking seed before planting.